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+% \iffalse meta-comment
+%
+% sudokubundle.dtx
+%
+% Author: Peter Wilson (Herries Press) herries dot press at earthlink dot net
+% Copyright 2006 Peter R. Wilson
+%
+% This work may be distributed and/or modified under the
+% conditions of the LaTeX Project Public License, either
+% version 1.3 of this license or (at your option) any
+% later version.
+% The latest version of the license is in
+% http://www.latex-project.org/lppl.txt
+% and version 1.3 or later is part of all distributions of
+% LaTeX version 2003/06/01 or later.
+%
+% This work has the LPPL maintenance status "author-maintained".
+%
+% This work consists of the files listed in the README file.
+%
+%<*driver>
+\documentclass[twoside]{ltxdoc}
+\usepackage{printsudoku}
+\usepackage{url}
+\usepackage[draft=false,
+ plainpages=false,
+ pdfpagelabels,
+ bookmarksnumbered,
+ hyperindex=false
+ ]{hyperref}
+\makeatletter
+ \@mparswitchfalse
+\makeatother
+\EnableCrossrefs
+\CodelineIndex
+%%% \RecordChanges
+%%%%%%%%%%%%% uncomment the next line to show all the code details
+%%\OnlyDescription
+%%% Don't use the default Short Verb.
+\AtBeginDocument{\DeleteShortVerb{\|}}
+%%% page headings to aid navigation, but I don't like Uppercased titles.
+\renewcommand{\MakeUppercase}[1]{#1}
+\pagestyle{headings}
+\setcounter{StandardModuleDepth}{1}
+\begin{document}
+ \DocInput{sudokubundle.dtx}
+\end{document}
+%</driver>
+%
+% \fi
+%
+% \CheckSum{5494}
+%
+% \DoNotIndex{\',\.,\@M,\@@input,\@addtoreset,\@arabic,\@badmath}
+% \DoNotIndex{\@centercr,\@cite}
+% \DoNotIndex{\@dotsep,\@empty,\@gobble,\@gobbletwo,\@ignoretrue}
+% \DoNotIndex{\@input,\@ixpt,\@m}
+% \DoNotIndex{\@minus,\@ne,\@nil,\@nomath,\@plus,\@set@topoint}
+% \DoNotIndex{\@tempboxa,\@tempcnta,\@tempdima,\@tempdimb}
+% \DoNotIndex{\@tempswafalse,\@tempswatrue,\@viipt,\@viiipt,\@vipt}
+% \DoNotIndex{\@vpt,\@warning,\@xiipt,\@xipt,\@xivpt,\@xpt,\@xviipt}
+% \DoNotIndex{\@xxpt,\@xxvpt,\\,\ ,\addpenalty,\addtolength,\addvspace}
+% \DoNotIndex{\advance,\Alph,\alph}
+% \DoNotIndex{\arabic,\ast,\begin,\begingroup,\bfseries,\bgroup,\box}
+% \DoNotIndex{\bullet}
+% \DoNotIndex{\cdot,\cite,\CodelineIndex,\cr,\day,\DeclareOption}
+% \DoNotIndex{\def,\DisableCrossrefs,\divide,\DocInput,\documentclass}
+% \DoNotIndex{\DoNotIndex,\egroup,\ifdim,\else,\fi,\em,\endtrivlist}
+% \DoNotIndex{\EnableCrossrefs,\end,\endgroup}
+% \DoNotIndex{\endlist,\everycr,\everypar,\ExecuteOptions,\expandafter}
+% \DoNotIndex{\fbox}
+% \DoNotIndex{\filedate,\filename,\fileversion,\fontsize,\framebox,\gdef}
+% \DoNotIndex{\global,\halign,\hbox,\hfil,\hfill,\hrule}
+% \DoNotIndex{\hsize,\hskip,\hspace,\hss,\if@tempswa,\ifcase,\or,\fi,\fi}
+% \DoNotIndex{\ifhmode,\ifvmode,\ifnum,\iftrue,\ifx,\fi,\fi,\fi,\fi,\fi}
+% \DoNotIndex{\input}
+% \DoNotIndex{\jobname,\kern,\leavevmode,\let}
+% \DoNotIndex{\list,\llap,\long,\m@ne,\m@th}
+% \DoNotIndex{\month,\newcommand,\newcounter,\newenvironment}
+% \DoNotIndex{\NeedsTeXFormat,\newdimen}
+% \DoNotIndex{\newlength,\newpage,\nobreak,\noindent,\null,\number}
+% \DoNotIndex{\numberline,\OldMakeindex,\OnlyDescription,\p@}
+% \DoNotIndex{\par,\paragraph,\paragraphmark,\parfillskip}
+% \DoNotIndex{\penalty,\PrintChanges,\PrintIndex,\ProcessOptions}
+% \DoNotIndex{\protect,\ProvidesClass}
+% \DoNotIndex{\refstepcounter,\relax,\renewcommand,\reset@font}
+% \DoNotIndex{\rightskip,\rlap,\rmfamily,\roman}
+% \DoNotIndex{\roman,\secdef,\selectfont,\setbox,\setcounter,\setlength}
+% \DoNotIndex{\settowidth,\sfcode,\skip,\sloppy,\slshape,\space}
+% \DoNotIndex{\symbol,\the,\trivlist,\typeout,\tw@,\undefined,\uppercase}
+% \DoNotIndex{\usecounter,\usefont,\usepackage,\vfil,\vfill,\viiipt}
+% \DoNotIndex{\viipt,\vipt,\vskip,\vspace}
+% \DoNotIndex{\wd,\xiipt,\year,\z@}
+% \DoNotIndex{\@namedef,\@nameuse,\csname,\endcsname}
+%
+% \def\dtxfile{sudokubundle.dtx}
+% \def\fileversion{1.0a} \def\filedate{2006/02/19}
+%
+% \newcommand*{\fref}[1]{Figure~\ref{#1}}
+% \newcommand*{\tref}[1]{Table~\ref{#1}}
+% \newcommand*{\Lopt}[1]{\textsf {#1}} ^^A typeset an option
+% \newcommand*{\file}[1]{\texttt {#1}} ^^A typeset a file
+% \newcommand*{\Lcount}[1]{\textsl {\small#1}} ^^A typeset a counter
+% \newcommand*{\pstyle}[1]{\textsl {#1}} ^^A typeset a pagestyle
+% \newcommand*{\Lenv}[1]{\texttt {#1}} ^^A typeset an environment
+% \newcommand*{\Lpack}[1]{\textsf {#1}} ^^A typeset a package
+% \newcommand*{\ctt}{\textsc{ctt}}
+% \newcommand{\Lclass}[1]{\textsf{#1}}
+% \newcommand{\PWcomment}[1]{}
+% \newenvironment{PW}{\itshape}{}
+% \renewenvironment{PW}{\sffamily}{}
+% \newcommand{\texbook}{\textit{TeXbook}}
+% \newcommand{\thetexbook}{\textit{The TeXbook}}
+% \newcommand{\egstart}{}
+% \newcommand{\egmid}{}
+% \newcommand{\egend}{}
+% \renewcommand{\egstart}{
+% \par
+% \begingroup
+% \centering
+% \begin{minipage}{0.45\textwidth}}
+% \renewcommand{\egmid}{
+% \end{minipage}\hfill\begin{minipage}{0.45\textwidth}}
+% \renewcommand{\egend}{
+% \end{minipage}\par\endgroup}
+%
+% \title{The sudoku bundle for displaying, solving and generating Sudoku
+% puzzles\thanks{This file (\dtxfile)
+% has version number \fileversion, last revised on \filedate.}}
+% \author{Peter
+% Wilson\thanks{\texttt{herries dot press at earthlink dot net}}\\
+% The Herries Press}
+% \date{\filedate}
+% \maketitle
+%
+% \begin{abstract}
+% The \Lpack{sudoku bundle} provides a coordinated set of packages for
+% displaying, solving, and generating Sudoku puzzles. A set of over 50 puzzles
+% is also supplied.
+% \end{abstract}
+%
+% \tableofcontents
+% \listoffigures
+%
+% \section{Introduction}
+%
+% In December 2005 the \emph{PracTeX Journal}~\cite{PRACTEX} set a competition
+% about Sudoku puzzles.
+% Depending on their experience with \TeX\ contestants were asked to
+% (a) typeset a particular puzzle, (b) typeset
+% a puzzle described in a `sudoku' file, (c) create a solver for
+% sudoku puzzles. I entered the competition with a printer and solver.
+% Following from this it was no great effort to develop a matching
+% Soduko puzzle generator.
+%
+% The packages described here have been developed completely independently
+% from Paul Abraham's \Lpack{sudoku} package~\cite{SUDOKU}, which I did
+% not see until after I had finished work on them.
+%
+% A Sudoku puzzle consists a 9 by 9 grid of cells with
+% some of the cells containing a number between 1 and 9, such as is
+% shown in \fref{fig:puz1}. The problem
+% is to place a number between 1 and 9 in each cell such that no number appears
+% more than once in each row and in each column and in each minor 3 by 3 grid.
+% The solution to the example puzzle is shown in \fref{fig:ans1}. The
+% puzzle and answer have been typeset using the \Lpack{printsudoku} package.
+%
+% \changes{v1.0a}{2006/02/19}{Deleted clue from example puzzle,
+% courtesy William Hammond}
+% \renewcommand*{\puzzlefile}{examout.sud}
+% \writepuzzle%
+% {..483..72}%
+% {.12....8.}%
+% {..52.13..}%
+% {....62.91}%
+% {7..5.9..3}%
+% {94.78....}%
+% {..39.74..}%
+% {.5....61.}%
+% {.8..469..}%
+% [Example puzzle \sudpuzznewline
+% (anything can come after the nine puzzle lines)]
+% \begin{figure}
+% \centering
+% \sudoku{examout.sud}
+% \caption{Example Sudoku puzzle}\label{fig:puz1}
+% \end{figure}
+%
+% Among many other sources the \emph{Sudoku Solver by logic}
+% website~\cite{SSBL}
+% provides much information on Sudoku puzzles and their solutions,
+% as does the \emph{Sudoku Online}~\cite{SOL} website.
+%
+% A Sudoku puzzle may be represented as a simple text file consisting
+% of nine rows of numbers and dots, nine numbers and dots in each row.
+% The numbers are the clues to the puzzle and the dots represent blanks
+% in the grid. A sudoko file for the example puzzle is given in
+% \fref{fig:file1}.
+%
+%
+% \begin{figure}
+% \centering
+% \begin{verbatim}
+% ..483..72
+% .12....8.
+% ..52.13..
+% ....62.91
+% 7..5.9..3
+% 94.78....
+% ..39.74..
+% .5....61.
+% .8..469..
+%
+% Example puzzle
+% (anything can come after the nine puzzle lines)
+% \end{verbatim}
+% \caption{A sudoku file for the example puzzle}\label{fig:file1}
+% \end{figure}
+%
+%
+% \renewcommand*{\puzzlefile}{examout.ans}
+% \writepuzzle%
+% {694835172}%
+% {312674589}%
+% {875291364}%
+% {538462791}%
+% {726519843}%
+% {941783256}%
+% {163957428}%
+% {459328617}%
+% {287146935}%
+% [Solution to example puzzle]
+%
+% \begin{figure}
+% \centering
+% \cluefont{\normalsize}\cellsize{1.5\baselineskip}
+% \sudoku{examout.ans}
+% \caption{Solution to example puzzle}\label{fig:ans1}
+% \end{figure}
+%
+%
+% This manual is typeset according to the conventions of the \LaTeX{}
+% \textsc{docstrip} utility which enables the automatic extraction
+% of the \LaTeX{} macro source files~\cite{COMPANION}.
+%
+% \section{Usage}
+%
+% The bundle provides three packages; one for typesetting a puzzle, one
+% for solving a puzzle, and the third for generating a puzzle. Each package
+% requires the previous one(s).
+%
+% A file is also provided that contains over 50 puzzles and their answers ---
+% all you have to do is run LaTeX on it, print it, and get to work on the puzzles
+% (or give them to someone else).
+%
+% \subsection{Typesetting}
+%
+% The \Lpack{printsudoku} package enables you to typeset a Sudoku
+% puzzle given in a sudoku file.
+%
+% \DescribeMacro{\sudoku}
+% The command \cs{sudoku}\marg{file} typesets the sudoku puzzle from the
+% sudoku file named \meta{file}.
+% For example: \\
+% \verb? \begin{center} \sudoku{puzzle1.sud} \end{center}? \\
+% The command reads only the first nine lines in the file, which must
+% contain the puzzle's description. Anything after these lines is ignored,
+% so comments, such as a title or other explanatory text,
+% can be put at the end of the file.
+%
+% \DescribeMacro{\cluefont}
+% Following \cs{cluefont}\marg{font} the clues are typeset using the
+% \meta{font} font specification. The default is: \\
+% \verb?\cluefont{\Huge}?
+%
+% \DescribeMacro{\cellsize}
+% The puzzle is typeset as a \LaTeX\ \Lenv{picture} and
+% \cs{cellsize}\marg{length} specifies the size of the cells in the grid.
+% To match the \cs{cluefont} the default is: \\
+% \verb?\cellsize{2.5\baselineskip}?
+%
+% Figure~\ref{fig:puz1} was set using the default \cs{cluefont} and
+% \cs{cellsize}. On the other hand, \fref{fig:ans1} was set via:
+% \begin{verbatim}
+% \begin{figure}
+% \centering
+% \cluefont{\normalsize}\cellsize{1.5\baselineskip}
+% \sudoku{examout.ans}
+% \caption{Solution to example puzzle}\label{fig:ans1}
+% \end{figure}
+% \end{verbatim}
+%
+% \DescribeMacro{\writepuzzle}
+% \DescribeMacro{\puzzlefile}
+% \DescribeMacro{\sudpuzznewline}
+% The command \cs{writepuzzle}, which takes nine required arguments each of
+% which is a line in the puzzle, writes the puzzle to the file \cs{puzzlefile}, where the default
+% is: \\
+% \verb?\newcommand*{\puzzlefile}{puzz.sud}?
+%
+% The nine required arguments to \cs{writepuzzle} are the lines describing
+% a puzzle as they would appear in a sudoku file. There is an optional tenth
+% argument after the nine required arguments which you may use to write
+% a comment at the end of the file.
+% For instance, earlier I used the following
+% to write out the example puzzle to the file \file{examout.sud}:
+% \begin{verbatim}
+% \renewcommand*{\puzzlefile}{examout.sud}
+% \writepuzzle%
+% {..483..72}%
+% {.12....8.}%
+% {..52.13..}%
+% {....62.91}%
+% {7..5.9..3}%
+% {94.78....}%
+% {..39.74..}%
+% {.5....61.}%
+% {.8..469..}%
+% [Example puzzle \sudpuzznewline
+% (anything can come after the nine puzzle lines)]
+% \end{verbatim}
+% And similarly for writing out the file with the solution.
+%
+% If you want a multiline comment, use the \cs{sudpuzznewline} macro to
+% start a new line (\verb?\\? or \cs{newline} will not work).
+%
+%
+% \subsection{Solving}
+%
+% The \Lpack{solvesudoku} package lets you use \LaTeX\ to try and solve
+% a Sudoku puzzle.
+%
+% \DescribeMacro{\sudokusolve}
+% The macro \cs{sudokusolve}\marg{file} attempts to find a solution to
+% the puzzle in the sudoku file \meta{file}. It uses the \Lpack{printsudoku}
+% package for typesetting the puzzle.
+%
+% It first prints the puzzle as given and then attempts to solve it.
+% The solution, or as much as was obtainable, is typeset in a smaller
+% font below the original. Here is the definition:
+% \begin{verbatim}
+% \newcommand*{\sudokusolve}[1]{%
+% \begin{center}
+% \sudoku{#1}
+% \end{center}
+% \getproblem{#1}
+% \reduceallcells \keepreducing
+% \writegame
+% \noindent\begin{minipage}{\linewidth}
+% THE ANSWER
+% \begin{center}
+% \cluefont{\normalsize}
+% \cellsize{1.5\baselineskip}
+% \sudoku{sud.out}
+% \end{center}
+% \end{minipage}}
+% \end{verbatim}
+% You may use the macros in \cs{sudokusolve} separately if you wish.
+%
+% \DescribeMacro{\getproblem}
+% \cs{getproblem}\marg{file} reads in the puzzle from the sudoku file
+% \meta{file} and initialises the solution.
+%
+% \DescribeMacro{\reduceallcells}
+% \cs{reduceallcells} takes a simple-minded approach to develop a solution
+% to the puzzle.
+%
+% \DescribeMacro{\keepreducing}
+% If \cs{reduceallcells} does not completely solve the puzzle then
+% \cs{keepreducing} applies increasingly sophisticated solution methods,
+% which may or may not lead to a complete solution.
+%
+% \DescribeMacro{\writegame}
+% \DescribeMacro{\sudsolnfile}
+% \cs{writegame} writes out a (partially) solved puzzle to the sudoku file
+% \cs{sudsolnfile} (default \file{sud.out}). Later this is read in again
+% by \cs{sudoku} to
+% typeset the solution.
+%
+% Here's a small example of how you might use the package. This will keep
+% asking on the terminal for sudoku files to solve.
+% \begin{verbatim}
+%%%% solvethem.tex Solve Sudoku files
+%%%% Peter Wilson
+% \documentclass{article}
+% \usepackage{solvesudoku}
+% \newcommand*{\solvefile}[1]{\begingroup
+% \sudokusolve{#1}%
+% \par
+% \vspace{\baselineskip}
+% Number of clues = \the\numcluesctr\ and difficulty = \the\difficultyctr.
+% \endgroup}
+% \def\yesans{y}
+% \begin{document}
+% \loop
+% \typein[\getans]{New file? y/n}
+% \ifx\yesans\getans
+% \typein[\sudfile]{Enter the file name}
+% \clearpage
+% \begin{center} \Huge \sudfile \end{center}
+% \solvefile{\sudfile}
+% \repeat
+% \end{document}
+% \end{verbatim}
+%
+% \DescribeMacro{\numcluesctr}
+% \DescribeMacro{\difficultyctr}
+% These are two \TeX\ \cs{count}s. \cs{numcluesctr} is the number of clues
+% in the initial puzzle, and \cs{difficultyctr} is a numerical indication
+% of how hard the solver had to work, but it doesn't really mean much
+% as the solver has had successes with some puzzles with a high
+% \cs{difficultyctr} rating
+% but failed to solve some with medium values of \cs{difficultyctr}.
+%
+% \subsection{Generation}
+%
+% With the \Lpack{createsudoku} package you can get \LaTeX\ to automatically
+% generate a Sudoku puzzle. This package does require the use of Donald
+% Arseneau's \Lpack{random} code~\cite{RANDOM} for generating random numbers.
+%
+% \DescribeMacro{\generategrid}
+% \cs{generategrid}\oarg{file} will generate a Sudoku puzzle starting with
+% the solution given in the sudoku file \meta{file}. If the file is
+% not given then it will start from a solution provided by the package.
+%
+% The puzzle is generated by taking the solution and randomly exchanging
+% rows and columns for some (random) number of times. Then clues are
+% eliminated until
+% it is no longer soluble by \cs{sudokusolve}. The last clue that was deleted
+% is put back and then the resulting grid is presented as the puzzle.
+%
+% An initial set of clues are deleted before the solver is called. It can
+% happen that the puzzle even then is too difficult for the solver, so
+% you have to check the solution as presented is a complete one for the puzzle.
+%
+% \DescribeMacro{\genfile}
+% \DescribeMacro{\prevfile}
+% \DescribeMacro{\currfile}
+% The generated puzzle, and its solution, is typeset and the puzzle is
+% also output in the sudoku file \cs{genfile}. The default is: \\
+% \verb?\newcommand*{\genfile}{gensud.sud}? \\
+% Two temporary sudoku files, \cs{prevfile} and \cs{currfile}, are
+% used during the generation. The defaults are: \\
+% \verb?\newcommand*{\prevfile}{genprev.sdx}? \\
+% \verb?\newcommand*{\currfile}{gencurr.sdx}? \\
+% A pre-existing version of any of these three files will be overwritten.
+%
+% \DescribeMacro{\setsudrandom}
+% The random number generater is initialised via a seed based on
+% a number (the internal value of \cs{randomi})
+% in the range $-1 \leq$ \cs{randomi} $\leq 2147483646$.
+% If its value is -1 (set via \verb?\setsudrandom{-1}?) then the actual
+% seed will be calculated based on the time and date. For any given
+% seed the sequence of the generated random numbers is the same.
+% The value of the
+% seed is output via a \cs{typeout} if you need to repeat a generation.
+%
+% You should not attempt to set \cs{randomi} directly but use
+% \cs{setsudrandom}\marg{num}.
+%
+% The default setting is: \\
+% \verb?\setsudrandom{-1}? \\
+% and as that means that the seed depends on the time and date,
+% a new puzzle will be
+% generated each time (unless the time interval is very short). The
+% maximum number of puzzles that can be generated from one initial solution
+% is 2,147,483,646 which is the range of the random number generator.
+%
+% \DescribeMacro{\initialelimination}
+% The macro \cs{initialelimination} eliminates an initial set of solutions
+% from the randomized starting grid. Various predefined sets are provided
+% and you can either provide your own definition for \cs{initialelimination}
+% or \cs{let} it to one of the predefined sets, e.g., \\
+% \verb?\let\initialelimination\elimcrossandnines?
+%
+% \DescribeMacro{\elimseventeen}
+% \DescribeMacro{\elimnum}
+% \DescribeMacro{\elimcross}
+% \DescribeMacro{\elimex}
+% \DescribeMacro{\elimcrossandnines}
+% \DescribeMacro{\elimcrossandex}
+% \DescribeMacro{\elimcrossandexandnines}
+% \cs{elimseventeen} randomly eliminates 17 solutions from the grid ---
+% apparently the solution to a puzzle can be ambiguous if two numbers
+% are completely absent.
+% \cs{elimnum}\marg{num} eliminates every solution \meta{num}
+% (e.g. \verb?\elimnum{7}? will eliminate every 7 from the grid).
+% \cs{elimcross} eliminates all numbers from column 5 and from row 5, while
+% \cs{elimex} eliminates all numbers on the diagonals.
+%
+% \cs{elimcrossandnines}
+% is a combination of \cs{elimcross} and \verb?\elimnum{9}?. Similarly the
+% macros \cs{elimcrossandex} and \cs{elimcrossandexandnines} are combinations
+% of some of the earlier macros.
+%
+%
+%
+% \StopEventually{
+% \bibliographystyle{alpha}
+% \begingroup
+% \raggedright
+% \begin{thebibliography}{GMSN94A}
+%
+% \bibitem[Abr05]{SUDOKU}
+% Paul Abraham.
+% \newblock \emph{The sudoku package}.
+% \newblock June 2005.
+% \newblock (Available from CTAN in
+% \texttt{macros/latex/contrib/sudoku})
+%
+% \bibitem[Ars95]{RANDOM}
+% Donald Arseneau.
+% \newblock \emph{Generating random numbers in \TeX}.
+% \newblock 1995.
+% \newblock (Available from CTAN in
+% \texttt{macros/generic/random.tex})
+%
+%
+% \bibitem[MG04]{COMPANION}
+% Frank Mittelbach and Michel Goossens.
+% \newblock \emph{The LaTeX Companion}.
+% \newblock Second edition.
+% \newblock Addison-Wesley Publishing Company, 2004.
+% \newblock \textsc{isbn} 0-201-36299-6.
+%
+% \bibitem[PJ05]{PRACTEX}
+% \TeX\ Users Group.
+% \newblock Distractions: Sudoku.
+% \newblock \emph{The PracTeX Journal}.
+% \newblock 2005-4.
+% \newblock \url{http://tug.org/pracjourn2005-4/distract}
+%
+% \bibitem[SOL]{SOL}
+% \emph{Sudoku Online: Home of the Sudokulist}.
+% \newblock \url{http://www.sudoku.org.uk}
+%
+% \bibitem[SSBL]{SSBL}
+% \emph{Sudoku Solver ... by logic}.
+% \newblock \url{http://www.sudokusolver.co.uk}
+%
+%
+% ^^A \bibitem[Wil04]{MEMOIR}
+% ^^A Peter Wilson.
+% ^^A \newblock \emph{The LaTeX \Lpack{memoir} class for configurable
+% ^^A typesetting: Source code}.
+% ^^A \newblock January 2004.
+% ^^A \newblock (Available from CTAN in
+% ^^A \texttt{macros/latex/contrib/memoir})
+%
+%
+% \end{thebibliography}
+% \endgroup
+%
+% \PrintIndex
+% }
+%
+% \section{Code}
+%
+% \subsection{The \Lpack{printsudoku} package}
+%
+% \begin{macrocode}
+%<*print>
+\NeedsTeXFormat{LaTeX2e}
+\ProvidesPackage{printsudoku}[2006/02/16 v1.0 typeset sudoku puzzles]
+
+% \end{macrocode}
+%
+% \begin{macro}{\s@dread}
+% \begin{macro}{\s@dwrite}
+% We are going to be reading and writing some files.
+% \begin{macrocode}
+\newread\s@dread
+\newwrite\s@dwrite
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\reads@dgame}
+% \cs{reads@dgame}\marg{file} opens a sudoku file \meta{file} for reading.
+% \begin{macrocode}
+%%%% open game file
+\newcommand*{\reads@dgame}[1]{%
+ \closein\s@dread
+ \openin\s@dread=#1}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\halfs@dcell}
+% \begin{macro}{\cellsize}
+% \begin{macro}{\cluefont}
+% We're going to use a \Lenv{picture} environment for drawing the grid,
+% and to keep numbers neatly we'll use the length \cs{halfs@dcell} as
+% the \cs{unitlength}. \cs{cellsize}\marg{length} is the use command for
+% setting the size of a cell. The clues are typeset using the \cs{cluefont}
+% font.
+% \begin{macrocode}
+%%% set size of a game cell
+\newlength\halfs@dcell
+\newcommand*{\cellsize}[1]{%
+ \halfs@dcell=#1\relax
+ \halfs@dcell=0.5\halfs@dcell}
+\cellsize{2.5\baselineskip}
+%% set font for the numbers
+\newcommand*{\cluefont}[1]{\def\s@dfont{#1}}
+\cluefont{\Huge}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\s@dncol}
+% \begin{macro}{\s@dnrow}
+% \begin{macro}{\s@dcolpos}
+% \begin{macro}{\s@drowpos}
+% Counts for looping and cell positions
+% \begin{macrocode}
+%% counts for looping and cell positions
+\newcount\s@dncol
+\newcount\s@dnrow
+\newcount\s@dcolpos
+\newcount\s@drowpos
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\adds@dclues}
+% \cs{adds@dclues} inserts the clues into the game grid. It reads the
+% sudoku file line by line insert the clues into the grid for one line
+% before going on to the next line.
+% \begin{macrocode}
+%% insert the clues into the game array
+\newcommand*{\adds@dclues}{%
+ \firsts@dcluetrue
+ \s@dnrow\@ne
+ \loop
+ \ifnum\s@dnrow<10\relax
+ \read\s@dread to \s@dline
+ \firsts@dcluetrue
+ \s@drowpos=\s@dnrow
+ \multiply\s@drowpos\tw@
+ \advance\s@drowpos\m@ne
+ \s@dncol\@ne
+ \dos@dcols
+ \advance\s@dnrow\@ne
+ \repeat
+ \closein\s@dread}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\dos@dcols}
+% \cs{dos@dcols} inserts one row of clues into the game grid.
+% \begin{macrocode}
+%% insert a row of clues
+\newcommand*{\dos@dcols}{%
+\bgroup
+ \loop
+ \ifnum\s@dncol<10\relax
+ \s@dcolpos=\s@dncol
+ \multiply\s@dcolpos\tw@
+ \advance\s@dcolpos\m@ne
+ \put(\s@dcolpos,-\s@drowpos){\makebox(0,0){\s@dfont\gets@dclue}}%
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\gettwo}
+% \begin{macro}{\nowt}
+% \begin{macro}{\istchar}
+% \begin{macro}{\restchars}
+% \begin{macro}{\splitoff}
+% \cs{splitoff}\marg{string} gets the next character in a string. The next
+% character is made available as \cs{istchar} and the remainder of the
+% string as \cs{restchars}. This is explained in a forthcoming
+% \emph{Glisterings} column in \emph{TUGboat}.
+% \begin{macrocode}
+%% get the next character in a string
+\def\gettwo#1#2\nowt{%
+ \gdef\istchar{#1}\gdef\restchars{#2}}
+\def\splitoff#1{\gettwo#1\nowt}
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\s@dfstop}
+% We use this for checking if a character extracted from a string is a `.'.
+% \begin{macrocode}
+%% a full stop (period)
+\gdef\s@dfstop{.}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\iffirsts@dclue}
+% \begin{macro}{\firsts@dcluetrue}
+% \begin{macro}{\firsts@dcluefalse}
+% \begin{macro}{\gets@dclue}
+% \cs{gets@dclue} gets the next clue (character) from a line of clues.
+% We do slightly different things if we are dealing with the first clue
+% or the others.
+% \begin{macrocode}
+%% get the next clue in the line
+\newif\iffirsts@dclue
+\firsts@dcluetrue
+\newcommand*{\gets@dclue}{%
+ \iffirsts@dclue
+ \expandafter\splitoff\expandafter{\s@dline}%
+ \global\firsts@dcluefalse
+ \else
+ \expandafter\splitoff\expandafter{\restchars}%
+ \fi
+ \ifx\s@dfstop\istchar
+ \else
+ \istchar
+ \fi}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\s@dgame}
+% \cs{s@dgame} typesets the grid, then adds in the clues.
+% \begin{macrocode}
+%% typeset the grid, then add the clues
+\newcommand*{\s@dgame}{%
+ \setlength\unitlength\halfs@dcell
+ \begin{picture}(18,18)(0,-18)
+ \thinlines
+ \multiput(0,0)(2,0){10}{\line(0,-1){18}}
+ \multiput(0,0)(0,-2){10}{\line(1,0){18}}
+ \thicklines \linethickness{1pt}
+ \multiput(0,0)(6,0){4}{\line(0,-1){18}}
+ \multiput(0,0)(0,-6){4}{\line(1,0){18}}
+ \adds@dclues
+ \end{picture}}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\sudoku}
+% \cs{sudoku}\marg{file} reads a game from \meta{file} and then typesets it.
+% \begin{macrocode}
+%% the whole shebang, where #1 is the name of the game file
+\newcommand*{\sudoku}[1]{%
+ \reads@dgame{#1}%
+ \s@dgame}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\puzzlefile}
+% \begin{macro}{\writepuzzle}
+% \begin{macro}{\writes@dpuzzend}
+% \begin{macro}{\sudpuzznewline}
+% \cs{writepuzzle} takes nine arguments --- the nine lines specifying a puzzle
+% --- and writes them to the \cs{puzzlefile} file.
+%
+% \cs{writes@dpuzzend}\oarg{comment} writes \meta{comment} at the end of the
+% \cs{puzzlefile} file.
+%
+% \cs{sudpuzznewline} provides a \cs{newline} macro for use in a comment being
+% written to a puzzle file.
+% \begin{macrocode}
+\newcommand*{\puzzlefile}{puzz.sud}
+\newcommand*{\writepuzzle}[9]{%
+ \immediate\closeout\s@dwrite
+ \immediate\openout\s@dwrite=\puzzlefile
+ \immediate\write\s@dwrite{#1}%
+ \immediate\write\s@dwrite{#2}%
+ \immediate\write\s@dwrite{#3}%
+ \immediate\write\s@dwrite{#4}%
+ \immediate\write\s@dwrite{#5}%
+ \immediate\write\s@dwrite{#6}%
+ \immediate\write\s@dwrite{#7}%
+ \immediate\write\s@dwrite{#8}%
+ \immediate\write\s@dwrite{#9}%
+ \writes@dpuzzend}
+\newcommand*{\writes@dpuzzend}[1][\@empty]{
+ \ifx\@empty #1\else
+ \immediate\write\s@dwrite{ }%
+ \immediate\write\s@dwrite{#1}%
+ \fi
+ \immediate\closeout\s@dwrite}
+\newcommand*{\sudpuzznewline}{^^J}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% The end of the package.
+% \begin{macrocode}
+%</print>
+% \end{macrocode}
+%
+% \subsection{The \Lpack{solvesudoku} package}
+%
+% The package requires the \Lpack{printsudoku} package to do some puzzle
+% typesetting.
+%
+% \begin{macrocode}
+%<*solve>
+\NeedsTeXFormat{LaTeX2e}
+\ProvidesPackage{solvesudoku}[2006/02/16 v1.0 solve sudoku puzzles]
+\RequirePackage{printsudoku}
+
+% \end{macrocode}
+%
+% \subsubsection{Setup}
+%
+% \begin{macro}{\commentary}
+% It can be useful to control the amount of output to the log file.
+% \begin{macrocode}
+\newcommand{\commentary}[1]{\typeout{#1}}
+
+% \end{macrocode}
+% \end{macro}
+%
+% The following counts are defined in the \Lpack{printsudoku} package: \\
+% \verb?\s@dncol, \s@dnrow, \s@dcolpos, \s@drowpos?
+%
+% \begin{macro}{\s@lcnta}
+% \begin{macro}{\solcnt}
+% \begin{macro}{\tenscnt}
+% \begin{macro}{\tempcntz}
+% \begin{macro}{\tempcnty}
+% \begin{macro}{\tmpsetctr}
+% \begin{macro}{\tmpsetansctr}
+% \begin{macro}{\boxctr}
+% \begin{macro}{\sumctr}
+% \begin{macro}{\toprangectr}
+% A bunch of \cs{count}s. They could probably be reduced in number
+% but they help me to keep the code less mysterious.
+% \begin{macrocode}
+%%% too many counts, maybe they should be reduced
+\newcount\s@lcnta % a cell number
+\newcount\solcnt % number of solved cells
+\newcount\settonumcnt
+\newcount\tenscnt
+\newcount\tempcntz
+\newcount\tempcnty
+\newcount\tmpsetctr
+\newcount\tmpsetansctr
+\newcount\boxctr
+\newcount\sumctr
+\newcount\toprangectr
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\lonecellctr}
+% \begin{macro}{\reducedctr}
+% \begin{macro}{\numlistctr}
+% \begin{macro}{\difficultyctr}
+% \begin{macro}{\s@dtempcnta}
+% \begin{macro}{\s@dtempcntb}
+% \begin{macro}{\s@dtemploopcnta}
+% \begin{macro}{\maxrangectr}
+% \begin{macro}{\asetctr}
+% \begin{macro}{\secondctr}
+% \begin{macrocode}
+\newcount\lonecellctr
+\newcount\reducedctr
+\newcount\numlistctr
+\newcount\difficultyctr
+\newcount\s@dtempcnta
+\newcount\s@dtempcntb
+\newcount\s@dtemploopcnta
+\newcount\maxrangectr
+\newcount\asetctr
+\newcount\secondctr
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\digitictr}
+% \begin{macro}{\digitiictr}
+% \begin{macro}{\numdigitsctr}
+% \begin{macro}{\numcluesctr}
+% \begin{macrocode}
+\newcount\digitictr
+\newcount\digitiictr
+\newcount\numdigitsctr
+\newcount\numcluesctr
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\iffirsts@dclue}
+% \begin{macro}{\iffirstchar}
+% \begin{macro}{\ifnotgotthechar}
+% \begin{macro}{\ifsetchanged}
+% \begin{macro}{\ifchanged}
+% \begin{macro}{\ifanychanged}
+% \begin{macro}{\iflonerchanged}
+% \begin{macro}{\ifstilldigits}
+% \begin{macro}{\ifkeepon}
+% \begin{macro}{\ifpairchanged}
+% \begin{macrocode}
+%%% \iffirsts@dclue% defined in printsudoku package
+\newif\iffirstchar
+\newif\ifnotgotthechar
+\newif\ifsetchanged
+\newif\ifchanged
+\newif\ifanychange
+\newif\iflonerchanged
+\newif\ifstilldigits
+\newif\ifkeepon
+\newif\ifpairchanged
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\newknt}
+% \begin{macro}{\useknt}
+% \begin{macro}{\createsudsets}
+% \cs{newknt}\marg{name} creates a new count \cs{name}, which can include
+% analphabetic characters. \cs{useknt}\marg{name} calls the \cs{name} count.
+% These are like the \LaTeX\ kernel \cs{@namedef} and \cs{@nameuse}.
+% In particular we will use 81 `numbered' counts, one for each cell
+% in the sudoku grid, using \cs{createsudsets} to generate them.
+% \begin{macrocode}
+%% create and use a numbered count
+%% we'll use 81 of these, one for each cell in the grid
+\newcommand*{\newknt}[1]{\expandafter\newcount\csname #1\endcsname}
+\newcommand*{\useknt}[1]{\csname #1\endcsname}
+%% create potential answer sets
+\newcommand*{\createsudsets}{%
+\global\s@lcnta\@ne
+\global\solcnt\z@
+\loop
+ \ifnum\s@lcnta<82\relax
+ \newknt{s@lans\the\s@lcnta}%
+ \advance\s@lcnta\@ne
+\repeat}
+\createsudsets
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsubsection{Binary solution sets}
+%
+% The major concern was deciding on the datastructure for the problem
+% (the value of \verb?\useknt{\s@lans\the\s@lcnta}}? for the \cs{s@lcnta} cell).
+% In the end I used a 9 digit `binary solution set' for the potential
+% solutions for
+% each cell. ($[111111111] \leftrightarrow 123456789$ and
+% $[101010101] \leftrightarrow 13579$). A cell
+% solution, say N, is represented as the `set' -N (e.g., a
+% potential solution 3 is represented as $[001000000]$ and the actual solution
+% 3 is represented by $[-3]$).
+%
+%
+% \begin{macro}{\initialisesuddata}
+% This sets each of the 81 cells to 111111111.
+% \begin{macrocode}
+%% initialise potential answer sets
+\newcommand*{\initialisesuddata}{\bgroup
+\global\s@lcnta\@ne
+\global\solcnt\z@
+\global\difficultyctr\z@
+\global\numcluesctr\z@
+\loop
+ \ifnum\s@lcnta<82\relax
+ \global\useknt{s@lans\the\s@lcnta}=111111111\relax
+ \advance\s@lcnta\@ne
+\repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%%%%%%%% utility macros for `binary solution sets' %%%%%%%%%%%%%%%%
+
+% \end{macrocode}
+%
+% \begin{macro}{\settonum}
+% \cs{settonum}\marg{set}\marg{cnt} converts a potential solution
+% binary set \meta{set} to the corresponding set of digits; that is
+% \verb?[11....1] -> 12...9?. The result of the conversion is assigned
+% to the \cs{count} \meta{cnt} which must be supplied by the calling macro.
+% If the set is negative then the result is that number
+% (e.g.\verb?[-3] -> -3?). If the set contains only a single non-zero
+% entry, that is converted to the negative of the corresponding digit
+% (e.g. \verb?[100] -> -7?).
+%
+% \begin{macrocode}
+%%\settonum{110011...}{cnt}
+%% converts a potential solution set to a number ([11....1] -> 12...9)
+%% returns the input if it is negative ([-3] -> -3)
+%% returns a negative number if the set represents a single digit ([10] -> -8)
+\newcommand*{\settonum}[2]{%
+ \settonumcnt=#1\relax
+ \tempcnty=\z@
+ \tenscnt=\@ne
+ \ifnum\settonumcnt<\z@ % just return the number
+ \tempcnty=\settonumcnt
+ #2=\tempcnty
+ \else
+ \ifodd\settonumcnt % 9 flagged
+ \tempcntz=9\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty by \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 8 flagged
+ \tempcntz=8\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 7 flagged
+ \tempcntz=7\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 6 flagged
+ \tempcntz=6\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 5 flagged
+ \tempcntz=5\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 4 flagged
+ \tempcntz=4\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 3 flagged
+ \tempcntz=3\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 2 flagged
+ \tempcntz=2\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+ \multiply\tenscnt 10\relax
+ \fi
+ \divide\settonumcnt by 10\relax
+ \ifodd\settonumcnt % 1 flagged
+ \tempcntz=1\relax
+ \multiply\tempcntz \tenscnt
+ \advance \tempcnty \tempcntz
+%% \multiply\tenscnt 10\relax
+ \fi
+ \ifnum \tempcnty<10
+ \ifnum\tempcnty>\z@
+ \tempcnty = -\tempcnty
+ \fi
+ \fi
+ #2=\tempcnty
+\fi}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\numofnuminset}
+% \cs{numofnuminset}\marg{digit}\marg{set}\marg{cnt} set the \cs{count}
+% \meta{cnt}to the number of times the digit \meta{digit} is represented
+% in the binary set \meta{set}. For example, the number of digits in the set
+% \verb?[200000013]? are \verb?1 -> 2?, \verb?2 -> 0?, \verb?...?,
+% \verb?8 -> 1? and \verb?9 -> 3?.
+% \begin{macrocode}
+%%\numofnuminset{digit}{set}{returnctr}
+%% returns the number of times digit is represented in the set
+%% e.g. if the set is [200000013] then 1 -> 2, 2 -> 0,... 8 -> 1, 9 -> 3
+\newcommand*{\numofnuminset}[3]{%
+ \tmpsetctr=#2\relax
+ \tmpsetansctr=\tmpsetctr
+ \ifnum\tmpsetctr<\z@% solution, not a set
+ \tmpsetansctr=\z@
+ \else
+ \ifcase #1\relax
+ \or % 1
+ \divide\tmpsetansctr by 100000000\relax
+ \or % 2
+ \divide\tmpsetansctr by 10000000\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 3
+ \divide\tmpsetansctr by 1000000\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 4
+ \divide\tmpsetansctr by 100000\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 5
+ \divide\tmpsetansctr by 10000\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 6
+ \divide\tmpsetansctr by 1000\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 7
+ \divide\tmpsetansctr by 100\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 8
+ \divide\tmpsetansctr by 10\relax
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \or % 9
+ \tmpsetctr=\tmpsetansctr
+ \divide\tmpsetctr 10\relax \multiply\tmpsetctr 10\relax
+ \advance\tmpsetansctr -\tmpsetctr
+ \else % error
+ \tmpsetansctr=\z@
+ \fi
+ \fi
+ #3=\tmpsetansctr}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\deletenumfromset}
+% \cs{deletenumfromset}\marg{digit}\marg{set}\marg{cnt} removes the
+% \meta{digit} from the \meta{set} and sets the \cs{count} \meta{cnt}
+% to the reulting modified set. If \meta{digit} was the only member
+% then the result is that digit negated. For example: \\
+% \verb?9? from \verb?[...11] -> [...10]? \\
+% \verb?8? from \verb?[0...010] -> -8?
+% \begin{macrocode}
+%%\deletenumfromset{digit}{set}{returnctr}
+%% deletes num from the [set], returning the modified set or a -ve number if
+%% the digit was the only member.
+%% e.g., 9 from [...11] -> [...10], 8 from [0...010] -> -8
+\newcommand*{\deletenumfromset}[3]{
+ \global\setchangedfalse
+ \tmpsetctr=#2\relax
+ \tmpsetansctr=#2\relax
+\ifnum\tmpsetctr<\z@ % represents a solved number, do nothing
+\else
+ \ifcase #1\relax
+ \or % 1
+ \divide\tmpsetctr by 100000000\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -100000000\relax
+ \global\setchangedtrue
+ \fi
+ \or % 2
+ \divide\tmpsetctr by 10000000\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -10000000\relax
+ \global\setchangedtrue
+ \fi
+ \or % 3
+ \divide\tmpsetctr by 1000000\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -1000000\relax
+ \global\setchangedtrue
+ \fi
+ \or % 4
+ \divide\tmpsetctr by 100000\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -100000\relax
+ \global\setchangedtrue
+ \fi
+ \or % 5
+ \divide\tmpsetctr by 10000\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -10000\relax
+ \global\setchangedtrue
+ \fi
+ \or % 6
+ \divide\tmpsetctr by 1000\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -1000\relax
+ \global\setchangedtrue
+ \fi
+ \or % 7
+ \divide\tmpsetctr by 100\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -100\relax
+ \global\setchangedtrue
+ \fi
+ \or % 8
+ \divide\tmpsetctr by 10\relax
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -10\relax
+ \global\setchangedtrue
+ \fi
+ \or % 9
+ \ifodd\tmpsetctr% it's there
+ \advance\tmpsetansctr -1\relax
+ \global\setchangedtrue
+ \fi
+ \fi
+\fi
+ #3=\tmpsetansctr}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\displaystatus}
+% This macro typesets a tabular showing the current real and potential
+% solutions for the grid. A real solution is shown as a negative number;
+% positive numbers are the potential solution digits for the cell.
+% \begin{macrocode}
+%% typeset current answers plus potential answer digits
+\newcommand*{\displaystatus}{%
+\begin{tabular}{||c|c|c||c|c|c||c|c|c||}\hline\hline
+\settonum{\the\useknt{s@lans1}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans2}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans3}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans4}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans5}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans6}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans7}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans8}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans9}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline
+\settonum{\the\useknt{s@lans10}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans11}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans12}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans13}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans14}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans15}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans16}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans17}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans18}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline
+\settonum{\the\useknt{s@lans19}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans20}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans21}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans22}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans23}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans24}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans25}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans26}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans27}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline\hline
+\settonum{\the\useknt{s@lans28}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans29}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans30}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans31}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans32}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans33}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans34}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans35}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans36}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline
+\settonum{\the\useknt{s@lans37}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans38}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans39}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans40}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans41}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans42}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans43}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans44}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans45}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline
+\settonum{\the\useknt{s@lans46}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans47}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans48}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans49}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans50}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans51}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans52}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans53}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans54}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline\hline
+\settonum{\the\useknt{s@lans55}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans56}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans57}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans58}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans59}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans60}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans61}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans62}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans63}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline
+\settonum{\the\useknt{s@lans64}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans65}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans66}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans67}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans68}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans69}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans70}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans71}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans72}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline
+\settonum{\the\useknt{s@lans73}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans74}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans75}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans76}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans77}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans78}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans79}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans80}}{\s@dtempcnta}\the\s@dtempcnta &
+\settonum{\the\useknt{s@lans81}}{\s@dtempcnta}\the\s@dtempcnta \\ \hline\hline
+\end{tabular}}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Problem initialisation}
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%%%% get the problem and initialise the solution %%%%%%%%%
+
+% \end{macrocode}
+%
+% \begin{macro}{\getproblem}
+% \cs{getproblem}\marg{file} initialises the solution grid and reads the
+% puzzle from the sudoku file \meta{file}. It calls \cs{initialsoln}
+% to read the file and insert the clues into the grid.
+% \begin{macrocode}
+%% read the problem and initialise the problem (solution)
+\newcommand*{\getproblem}[1]{\bgroup
+ \initialisesuddata
+ \global\solcnt\z@
+ \immediate\closein\s@dread
+ \immediate\openin\s@dread=#1
+ \initialsoln
+ \typeout{Sudoku problem #1, \the\solcnt\space initial clues}
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\initialsoln}
+% Get the clues from the puzzle file, line by line, and insert them into
+% the grid. \cs{s@dline} holds one line from the file.
+% \begin{macrocode}
+%% insert the clues from the input game file
+\newcommand*{\initialsoln}{%
+ \firsts@dcluetrue
+ \s@dnrow\@ne
+ \s@lcnta\@ne
+ \loop
+ \ifnum\s@dnrow<10\relax
+ \read\s@dread to \s@dline
+ \firsts@dcluetrue
+ \s@dncol\@ne
+ \dos@dinitialcols
+ \advance\s@dnrow\@ne
+ \repeat
+ \immediate\closein\s@dread}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\dos@dinitialcols}
+% Insert the clues from one line of the puzzle file into one row of the grid.
+% \begin{macrocode}
+%% insert the clues from one line of the game file
+\newcommand*{\dos@dinitialcols}{\bgroup
+ \loop
+ \ifnum\s@dncol<10\relax
+ \fixentry
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\fixentry}
+% Inserts a clue from the current line into the grid.
+% \begin{macrocode}
+%% insert a clue from the current line of the game file
+\newcommand*{\fixentry}{%
+ \iffirsts@dclue
+ \expandafter\splitoff\expandafter{\s@dline}%
+ \global\firsts@dcluefalse
+ \else
+ \expandafter\splitoff\expandafter{\restchars}%
+ \fi
+ \ifx\s@dfstop\istchar
+ \else
+ \global\useknt{s@lans\the\s@lcnta}=-\istchar
+ \global\advance\solcnt\@ne
+ \global\advance\numcluesctr\@ne
+ \fi
+ \global\advance\s@lcnta\@ne}
+
+
+% \end{macrocode}
+% \end{macro}
+%
+% \subsection{Solution methods}
+%
+%
+% Three facts are used to generate a solution.
+% \begin{enumerate}
+% \item A digit must be unique within a row, a column, and a block
+% Thus, if a solution, say N, is known for a cell, then the
+% potential solution N must be deleted from all cells in the
+% row, column, and block that the solved cell is in. I have
+% called this a simple reduction. The simple reductions are repeated
+% until there are no changes to the potential solutions.
+%
+% \item If among all the cells in a row (column, block) there is a digit
+% that occurs only once among all the potential solutions, then that
+% digit is the solution for its cell. I have termed this a loner.
+% If a loner solution is found then simple reductions are repeated.
+%
+% \item If among all the cells in a row (column, block) there are two digits
+% which occur twice only in the row, each time as a pair (e.g., 39
+% and 39) then one or other of the two digits must be a solution for
+% a cell in which the pairs occur. This means that the two digits in
+% the pair cannot occur anywhere else in the row (column, block).
+% If there are no loners then the problem is examined for pairs. If
+% there is any change in a potential solution then the simple
+% reduction process is applied.
+% \end{enumerate}
+%
+% The process stops either when all 81 cells have been solved or there
+% is no change in any potential solution after going through all the above
+% reductions.
+%
+% There are more sophisticated solution techniques that could be applied
+% but they are also increasingly difficult to code in \TeX.
+%
+% \begin{macro}{\reduceacell}
+% \cs{reduceacell} looks at the solution set for the current cell (the
+% \cs{s@lcnta} cell) and if the cell has been solved then it deletes the
+% solution digit from the row, column, and box in which the cell appears.
+% This may result in new solutions for other cells.
+%
+% Given a cell number $N$ ($0<N<82$) and, using integer arithmetic,
+% putting $M = (N-1)/9$ then
+% \begin{itemize}
+% \item Cell number $C$ at top of column: $C = N - 9M$
+% \item Cell number $R$ at left of row: $R = 9M + 1$
+% \item Cell number $b$ at top left of 3 by 3 box:
+% $B = 27(M/3) + 3((N-1-9M)/3) + 1$
+% \end{itemize}
+%
+% \begin{macrocode}
+%% Eliminate a solution digit from its row, column and box.
+%% This may result in some new solutions.
+\newcommand*{\reduceacell}{\bgroup
+ \ifnum\useknt{s@lans\the\s@lcnta}<\z@ % solved cell
+ \s@dtempcnta=-\useknt{s@lans\the\s@lcnta}
+%% get the col, row and box numbers
+ \tempcnty=\s@lcnta % M in the formulae
+ \advance\tempcnty\m@ne \divide\tempcnty 9\relax
+ \tempcntz=\tempcnty \multiply\tempcntz 9\relax
+ \s@dcolpos=\s@lcnta \advance\s@dcolpos -\tempcntz % col
+ \s@drowpos\tempcntz \advance\s@drowpos\@ne % row
+ \boxctr=\tempcnty % box
+ \divide\boxctr\thr@@ \multiply\boxctr 27\relax
+ \tempcnty=\s@lcnta % reuse \tempcnty
+ \advance\tempcnty\m@ne \advance\tempcnty -\tempcntz
+ \divide\tempcnty\thr@@ \multiply\tempcnty \thr@@
+ \advance\boxctr\tempcnty \advance\boxctr \@ne
+%% reduce the row, column, and the box
+ \reducerow{\the\s@drowpos}{\the\s@dtempcnta}
+ \reducecol{\the\s@dcolpos}{\the\s@dtempcnta}
+ \reducebox{\the\boxctr}{\the\s@dtempcnta}
+ \fi
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducerow}
+% \cs{reducerow}\marg{row}\marg{digit} eliminates \meta{digit} from the
+% binary solution sets of the cells in the row starting at cell number
+% \meta{row}.
+% \begin{macrocode}
+%% \reducerow{rowcellnumber}{digit}
+%% simple reduction for digit in a row
+\newcommand*{\reducerow}[2]{\bgroup
+ \s@dncol=#1\relax
+ \toprangectr=\s@dncol
+ \advance\toprangectr 9\relax
+ \bgroup
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \deletenumfromset{#2}{\the\useknt{s@lans\the\s@dncol}}{\reducedctr}
+ \ifsetchanged
+ \global\changedtrue
+ \settonum{\the\reducedctr}{\numlistctr}
+ \ifnum\numlistctr<10\relax
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved
+ (\the\s@dncol\space = \the\numlistctr\space in row starting #1)}%
+ \global\useknt{s@lans\the\s@dncol}=\numlistctr
+ \else
+ \global\useknt{s@lans\the\s@dncol}=\reducedctr
+ \fi
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+ \egroup
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducecol}
+% \cs{reducecol}\marg{col}\marg{digit} eliminates \meta{digit} from the
+% binary solution sets of the cells in the column starting at cell number
+% \meta{col}.
+% \begin{macrocode}
+%% \reducecol{colcellnumber}{digit}
+%% simple reduction of a digit in a column
+\newcommand*{\reducecol}[2]{\bgroup
+ \s@dnrow=#1\relax
+ \toprangectr=\s@dnrow
+ \advance\toprangectr 73\relax
+ \bgroup
+ \loop
+ \ifnum\s@dnrow<\toprangectr
+ \deletenumfromset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\reducedctr}
+ \ifsetchanged
+ \global\changedtrue
+ \settonum{\the\reducedctr}{\numlistctr}
+ \ifnum\numlistctr<10\relax
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved
+ (\the\s@dnrow\space = \the\numlistctr\space in column starting #1)}%
+ \global\useknt{s@lans\the\s@dnrow}=\numlistctr
+ \else
+ \global\useknt{s@lans\the\s@dnrow}=\reducedctr
+ \fi
+ \fi
+ \advance\s@dnrow 9\relax
+ \repeat
+ \egroup
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducebox}
+% \cs{reducebox}\marg{box}\marg{digit} eliminates \meta{digit} from the
+% binary solution sets of the cells in the box starting at cell number
+% \meta{box}.
+% \begin{macrocode}
+%% \reducebox{boxcellnumber}{digit}
+%% simple reduction of a digit in a box
+\newcommand*{\reducebox}[2]{\bgroup
+ \s@dncol=#1\relax
+ \toprangectr=\s@dncol
+ \advance\toprangectr \thr@@
+ \bgroup
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \s@dnrow=\s@dncol
+ \deletenumfromset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\reducedctr}
+ \ifsetchanged
+ \global\changedtrue
+ \settonum{\the\reducedctr}{\numlistctr}
+ \ifnum\numlistctr<10\relax
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved
+ (\the\s@dnrow\space = \the\numlistctr\space in box starting #1)}%
+ \global\useknt{s@lans\the\s@dnrow}=\numlistctr
+ \else
+ \global\useknt{s@lans\the\s@dnrow}=\reducedctr
+ \fi
+ \fi
+ \advance\s@dnrow 9\relax
+ \deletenumfromset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\reducedctr}
+ \ifsetchanged
+ \global\changedtrue
+ \settonum{\the\reducedctr}{\numlistctr}
+ \ifnum\numlistctr<10\relax
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved
+ (\the\s@dnrow\space = \the\numlistctr\space in box starting #1)}%
+ \global\useknt{s@lans\the\s@dnrow}=\numlistctr
+ \else
+ \global\useknt{s@lans\the\s@dnrow}=\reducedctr
+ \fi
+ \fi
+ \advance\s@dnrow 9\relax
+ \deletenumfromset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\reducedctr}
+ \ifsetchanged
+ \global\changedtrue
+ \settonum{\the\reducedctr}{\numlistctr}
+ \ifnum\numlistctr<10\relax
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved
+ (\the\s@dnrow\space = \the\numlistctr\space in box starting #1)}%
+ \global\useknt{s@lans\the\s@dnrow}=\numlistctr
+ \else
+ \global\useknt{s@lans\the\s@dnrow}=\reducedctr
+ \fi
+ \fi
+ \advance\s@dncol \@ne
+ \repeat
+ \egroup
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reduceallcells}
+% \cs{reduceallcells} examines all 81 cells, eliminating solution digits
+% from the binary solution sets of the other cells in the row, column, and box.
+% \begin{macrocode}
+%% loop over every cell, removing solution digits from the potential sets
+%% in the cell's row, column and box.
+\newcommand*{\reduceallcells}{\bgroup
+ \ifnum\difficultyctr<\@ne
+ \global\difficultyctr\@ne
+ \fi
+ \s@lcnta\@ne
+ \global\changedfalse
+ \loop
+ \ifnum\s@lcnta<82\relax
+ \reduceacell
+ \advance\s@lcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\keepreducing}
+% \cs{keepreducing} performs simple reductions on all the cells until either
+% the puzzle is solved or no changes have been made. It then tries loner
+% reductions, returning to simple reductions following any change. If
+% no change has been made after loner reductions it then tries pair reductions.
+% After any change it goes back to simple reductions. This iterative process
+% continues until either the puzzle has been solved (\cs{solcnt} = 81)
+% or no further changes can be made.
+%
+% A measure of the difficulty of the puzzle could be made by incrementing a
+% count
+% each time a new kind of reduction is tried. The increment increases with
+% the complexity of the reduction.
+%
+% \begin{macrocode}
+\newcommand*{\keepreducing}{%
+ \anychangetrue
+ \keepontrue
+ \loop
+ \ifkeepon
+ \keepreducingcells
+ \ifnum\solcnt<81\relax
+%%% \advance\difficultyctr 4\relax
+ \reduceloners
+ \fi
+ \anychangefalse
+ \iflonerchanged
+ \anychangetrue
+ \fi
+ \ifanychange\else
+ \ifnum\solcnt<81\relax
+%%% \advance\difficultyctr 8\relax
+ \pairchangedfalse
+ \reducepairs
+ \ifpairchanged
+ \anychangetrue
+ \fi
+ \fi
+ \fi
+ \checkkeepon
+ \repeat
+ \ifnum\solcnt<81\relax
+ \global\multiply \difficultyctr 10\relax
+ \fi
+\typeout{************ Number of solutions = \the\solcnt}
+\typeout{************ Difficulty rating = \the\difficultyctr}
+}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\checkkeepon}
+% Determines whether or not to keep on trying to reach the solution.
+% \begin{macrocode}
+\newcommand*{\checkkeepon}{%
+ \ifnum\solcnt>80\relax
+ \keeponfalse
+ \fi
+ \ifanychange\else
+ \keeponfalse
+ \fi}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\keepreducingcells}
+% Keep on trying the simple reduction.
+% \begin{macrocode}
+%% Keep performing the simple reduction
+\newcommand*{\keepreducingcells}{\bgroup
+\commentary{Simple reductions}%
+ \ifnum\difficultyctr<\tw@
+ \global\difficultyctr\tw@
+ \fi
+ \changedtrue
+ \loop
+ \ifchanged
+ \reduceallcells
+ \checksimplereductions
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\checksimplereductions}
+% Determines whether or not to keep on trying simple reductions.
+% \begin{macrocode}
+\newcommand*{\checksimplereductions}{%
+ \ifchanged\else
+ \typesimplestatus
+ \fi
+ \ifnum\solcnt>80\relax% solution found!
+ \changedfalse
+ \fi}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%%%%% reduce loners %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+% \end{macrocode}
+%
+% \begin{macro}{\reduceloners}
+% Reduce via the loner digits, trying rows first, and if no change
+% then trying columns, and if still no change then trying boxes.
+% \begin{macrocode}
+%% reduce the loner digits, per row, column and box
+\newcommand*{\reduceloners}{%
+\commentary{reduceloners}%
+ \global\lonerchangedfalse
+ \ifnum\difficultyctr<4\relax
+ \global\difficultyctr=4\relax
+ \fi
+ \ifnum\solcnt>80\else
+ \bgroup
+ \reducerowloners
+ \iflonerchanged\else
+ \reducecolloners
+ \iflonerchanged\else
+ \reduceboxloners
+ \fi
+ \fi
+ \typelonestatus
+ \egroup
+ \fi}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducerowloners}
+% Loop through the rows and reduce the first loner found.
+% \begin{macrocode}
+%% Loop through the rows, reducing loners
+\newcommand*{\reducerowloners}{%
+ \sumctr\z@
+ \s@dnrow\@ne
+ \loop
+ \ifnum\s@dnrow<10\relax
+ \s@lcnta=\s@dnrow \advance\s@lcnta\m@ne
+ \multiply\s@lcnta 9\relax \advance\s@lcnta\@ne
+ \sumrowsets
+ \ifnum\sumctr>\z@
+ \getloner{\the\sumctr}{\s@dtempcntb}
+ \ifnum\s@dtempcntb=\z@
+ \else
+ \reducelonerrowcell{\the\s@lcnta}{\the\s@dtempcntb}
+ \iflonerchanged
+ \advance\s@dnrow 10\relax
+ \fi
+ \fi
+ \fi
+ \advance\s@dnrow\@ne
+ \repeat}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\sumrowsets}
+% Add together all the solution binary sets for the unsolved cells
+% in the current row (\cs{s@lcnta}). The result is in \cs{sumctr}.
+% \begin{macrocode}
+%% add the sets in the current row
+\newcommand*{\sumrowsets}{%
+ \bgroup
+ \s@dncol=\s@lcnta
+ \toprangectr=\s@dncol
+ \advance\toprangectr 9\relax
+ \global\sumctr\z@
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \ifnum\useknt{s@lans\the\s@dncol}>\z@
+ \global\advance\sumctr\useknt{s@lans\the\s@dncol}
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\getloner}
+% \cs{getloner}\marg{setsum}\marg{cnt} examines (the sum of) a solution set
+% and returns the first loner (i.e., the first occurrence of the digit 1), or
+% zero if there is none. The result is converted to a solution digit and
+% assigned to the \cs{count} \meta{cnt}.
+%
+% For example, given the set \verb?[000200110]? it will return \verb?7? (the
+% set indicates two 4s, one 7, and one 8).
+% \begin{macrocode}
+%% get the loner from a setsum
+%% \getloner{setsum}{returnctr} returnes the (first) loner in a potential set,
+%% or zero
+\newcommand*{\getloner}[2]{\bgroup
+ \ifnum #1>\z@
+ \s@dtemploopcnta\@ne
+ \loop
+ \ifnum\s@dtemploopcnta<10\relax
+ \numofnuminset{\the\s@dtemploopcnta}{#1}{\s@dtempcnta}
+ \ifnum\s@dtempcnta=\@ne% found a lone digit
+ \s@dtempcnta=\s@dtemploopcnta
+ \s@dtemploopcnta=100\relax
+ \fi
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+ \ifnum\s@dtemploopcnta>99 \else \s@dtempcnta=\z@ \fi
+ \global#2=\s@dtempcnta
+ \else
+ \s@dtempcnta=\z@
+ \global#2=\s@dtempcnta
+ \fi
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducelonerowcell}
+% \cs{reducelonerowcell}\marg{rowcell}\marg{digit}.
+% Given (the cell at) the start of a row and a lone digit, find the cell
+% in the row with that digit in its solution set, and make the digit the
+% solution of that cell.
+% \begin{macrocode}
+%% \reducelonerowcell{startofrowcell}{digit}
+%% given a row and a lone digit, find the cell containing the digit
+%% and make the digit a solution of that cell.
+\newcommand*{\reducelonerrowcell}[2]{\bgroup
+ \s@dncol=#1
+ \toprangectr=\s@dncol
+ \advance\toprangectr 9\relax
+ \ifnum #2<\@ne
+ \advance\s@dncol 100\relax
+ \fi
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \numofnuminset{#2}{\the\useknt{s@lans\the\s@dncol}}{\lonecellctr}
+ \ifnum\lonecellctr=\@ne% this cell has the loner
+ \lonecellctr=#2
+ \global\useknt{s@lans\the\s@dncol}=-\lonecellctr
+ \global\lonerchangedtrue
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved (#2 loner in row starting #1)}%
+ \s@dncol=\toprangectr
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducecolloners}
+% Loop through the columns and reduce the first loner found.
+% \begin{macrocode}
+%% Loop through the columns, reducing loners
+\newcommand*{\reducecolloners}{\bgroup
+ \sumctr\z@
+ \s@dncol\@ne
+ \loop
+ \ifnum\s@dncol<10\relax
+ \s@lcnta=\s@dncol
+ \sumcolsets
+ \ifnum\sumctr>\z@
+ \getloner{\the\sumctr}{\s@dtempcntb}
+ \ifnum\s@dtempcntb=\z@
+ \else
+ \reducelonercolcell{\the\s@lcnta}{\the\s@dtempcntb}
+ \iflonerchanged
+ \advance\s@dncol 10\relax
+ \fi
+ \fi
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\sumcolsets}
+% Sum all the solution sets of the unsolved cells in the current column
+% (\cs{s@lcnta}). The result is in \cs{sumctr}.
+% \begin{macrocode}
+%% add the sets in the current column
+\newcommand*{\sumcolsets}{\bgroup
+ \s@dnrow=\s@lcnta
+ \toprangectr=\s@dnrow
+ \advance\toprangectr 73\relax
+ \global\sumctr\z@
+ \loop
+ \ifnum\s@dnrow<\toprangectr
+ \ifnum\useknt{s@lans\the\s@dnrow}>\z@
+ \global\advance\sumctr\useknt{s@lans\the\s@dnrow}
+ \fi
+ \advance\s@dnrow 9\relax
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducelonercolcell}
+% \cs{reducelonercolcell}\marg{colcell}\marg{digit}.
+% Given (the cell at) the start of a column and a lone digit, find the cell
+% in the column with that digit in its solution set, and make the digit
+% the solution of that cell.
+% \begin{macrocode}
+%% \reducelonercolcell{startofcolcell}{digit}
+%% given a col and a lone digit, find the cell containing the digit
+%% and make the digit a solution of that cell.
+\newcommand*{\reducelonercolcell}[2]{\bgroup
+ \s@dnrow=#1
+ \toprangectr=\s@dnrow
+ \advance\toprangectr 73\relax
+ \ifnum #2<\@ne
+ \advance\s@dnrow 7300\relax
+ \fi
+ \loop
+ \ifnum\s@dnrow<\toprangectr
+ \numofnuminset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\lonecellctr}
+ \ifnum\lonecellctr=\@ne% this cell has the loner
+ \lonecellctr=#2
+ \global\useknt{s@lans\the\s@dnrow}=-\lonecellctr
+ \global\lonerchangedtrue
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved (#2 loner in column starting #1)}%
+ \s@dnrow=\toprangectr
+ \fi
+ \advance\s@dnrow 9\relax
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reduceboxloners}
+% Loop through the boxes and reduce the first loner found.
+% \begin{macrocode}
+%% Loop through the boxes, reducing loners
+\newcommand*{\reduceboxloners}{\bgroup
+ \sumctr\z@
+ \boxctr\@ne
+ \loop
+ \ifnum\boxctr<10\relax
+% \end{macrocode}
+% The next bit of code calculates the corner cell of the Nth box.
+% \begin{macrocode}
+ \ifcase\boxctr
+ \or \s@lcnta=\@ne
+ \or \s@lcnta=4\relax
+ \or \s@lcnta=7\relax
+ \or \s@lcnta=28\relax
+ \or \s@lcnta=31\relax
+ \or \s@lcnta=34\relax
+ \or \s@lcnta=55\relax
+ \or \s@lcnta=58\relax
+ \or \s@lcnta=61\relax
+ \fi
+ \sumboxsets
+ \ifnum\sumctr>\z@
+ \getloner{\the\sumctr}{\s@dtempcntb}
+ \ifnum\s@dtempcntb=\z@
+ \else
+ \reducelonerboxcell{\the\s@lcnta}{\the\s@dtempcntb}
+ \iflonerchanged
+ \advance\boxctr 10\relax
+ \fi
+ \fi
+ \fi
+ \advance\boxctr\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\sumboxsets}
+% Sum all the solution sets of the unsolved cells in the current box
+% (\cs{s@lcnta}). The result is in \cs{sumctr}.
+% \begin{macrocode}
+%% add the sets in the current box
+\newcommand*{\sumboxsets}{\bgroup
+ \s@dncol=\s@lcnta
+ \toprangectr=\s@dncol
+ \advance\toprangectr 3\relax
+ \global\sumctr\z@
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \s@dnrow=\s@dncol
+ \ifnum\useknt{s@lans\the\s@dnrow}>\z@
+ \global\advance\sumctr\useknt{s@lans\the\s@dnrow}
+ \fi
+ \advance\s@dnrow 9\relax
+ \ifnum\useknt{s@lans\the\s@dnrow}>\z@
+ \global\advance\sumctr\useknt{s@lans\the\s@dnrow}
+ \fi
+ \advance\s@dnrow 9\relax
+ \ifnum\useknt{s@lans\the\s@dnrow}>\z@
+ \global\advance\sumctr\useknt{s@lans\the\s@dnrow}
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducelonerboxcell}
+% \cs{reducelonerboxcell}\marg{boxcell}\marg{digit}.
+% Given (the cell at) the start of a box and a lone digit, find the cell
+% in the box with that digit in its solution set, and make the digit
+% the solution of that cell.
+% \begin{macrocode}
+%% \reducelonerboxcell{startofboxcell}{digit}
+%% given a box and a lone digit, find the cell containing the digit
+%% and make the digit a solution of that cell.
+\newcommand*{\reducelonerboxcell}[2]{\bgroup
+ \s@dncol=\s@lcnta
+ \toprangectr=\s@dncol
+ \advance\toprangectr 3\relax
+ \global\sumctr\z@
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \s@dnrow=\s@dncol
+ \numofnuminset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\lonecellctr}
+ \ifnum\lonecellctr=\@ne% this cell has the loner
+ \lonecellctr=#2
+ \global\useknt{s@lans\the\s@dnrow}=-\lonecellctr
+ \global\lonerchangedtrue
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved (#2 loner in box starting #1)}%
+ \s@dncol=\toprangectr
+ \fi
+ \iflonerchanged\else
+ \advance\s@dnrow 9\relax
+ \numofnuminset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\lonecellctr}
+ \ifnum\lonecellctr=\@ne% this cell has the loner
+ \lonecellctr=#2
+ \global\useknt{s@lans\the\s@dnrow}=-\lonecellctr
+ \global\lonerchangedtrue
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved (#2 loner in box starting #1)}%
+ \s@dncol=\toprangectr
+ \fi
+ \fi
+ \iflonerchanged\else
+ \advance\s@dnrow 9\relax
+ \numofnuminset{#2}{\the\useknt{s@lans\the\s@dnrow}}{\lonecellctr}
+ \ifnum\lonecellctr=\@ne% this cell has the loner
+ \lonecellctr=#2
+ \global\useknt{s@lans\the\s@dnrow}=-\lonecellctr
+ \global\lonerchangedtrue
+ \global\advance\solcnt\@ne
+\commentary{\the\solcnt\space solved (#2 loner in box starting #1)}%
+ \s@dncol=\toprangectr
+ \fi
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%%%%% reduce pairs %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+% \end{macrocode}
+%
+% \begin{macro}{\reducepairs}
+% Perform pair reduction, reducing the first pair found. First try
+% by row, then by column, and lastly by box.
+% \begin{macrocode}
+%% reduce the pairs, per row, column and box
+\newcommand*{\reducepairs}{\bgroup
+\commentary{reducepairs}% **************************************}%
+ \global\pairchangedfalse
+ \ifnum\difficultyctr<8\relax
+ \global\difficultyctr=8\relax
+ \fi
+ \ifnum\solcnt>80\else
+ \reducerowpairs
+ \ifpairchanged\else
+ \reducecolpairs
+ \ifpairchanged\else
+ \reduceboxpairs
+ \fi
+ \fi
+ \fi
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducerowpairs}
+% Loop through the rows and reduce the first pair found.
+% \begin{macrocode}
+%% Loop through the rows, reducing pairs
+\newcommand*{\reducerowpairs}{%
+ \sumctr\z@
+ \s@dnrow\@ne
+ \loop
+ \ifnum\s@dnrow<10\relax
+ \s@lcnta=\s@dnrow \advance\s@lcnta\m@ne
+ \multiply\s@lcnta 9\relax \advance\s@lcnta\@ne
+ \sumrowsets
+ \ifnum\sumctr>\z@
+ \reducearowpair{\the\s@lcnta}
+ \ifpairchanged
+ \advance\s@dnrow 10\relax
+ \fi
+ \fi
+ \advance\s@dnrow\@ne
+ \repeat}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducearowpair}
+% \cs{reducearowpair}\marg{rowcell} reduces a pair in the row starting
+% with cell \meta{rowcell}.
+% \begin{macrocode}
+%% reducearowpair{row}
+\newcommand*{\reducearowpair}[1]{%
+ \bgroup
+ \s@dncol=#1\relax
+ \toprangectr=\s@dncol
+ \advance\toprangectr 9\relax
+ \maxrangectr=\toprangectr
+ \advance\maxrangectr\m@ne
+ \global\sumctr\z@
+ \loop
+ \ifnum\s@dncol<\maxrangectr
+ \asetctr=\useknt{s@lans\the\s@dncol}%
+ \ifnum\asetctr>\z@
+ \findrowpair
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\findrowpair}
+% \cs{findrowpair} attempts to find a pair in the current row.
+% \begin{macrocode}
+\newcommand*{\findrowpair}{\bgroup
+ \secondctr=\s@dncol
+ \advance\secondctr\@ne
+ \loop
+ \ifnum\secondctr<\toprangectr
+ \ifnum\asetctr=\useknt{s@lans\the\secondctr}
+ \checksetforpair{\the\asetctr}
+ \ifnum\numdigitsctr=\tw@
+%% first row cell is \s@lcnta
+%% first pair cell is \s@dncol, second pair cell is \secondctr
+%% digits are \digitictr and \digitiictr
+ \deleterowpairdigits
+ \fi
+ \fi
+ \advance\secondctr\@ne
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\checksetforpair}
+% \cs{checksetforpair}\marg{set} attempts to find a pair in a set.
+% It sets \cs{digitictr} and \cs{digitiictr} as the first and second digits
+% in the set and \cs{numdigitsctr} to the total number of digits in the
+% set (which is 2 for a pair).
+% \begin{macrocode}
+%% \checksetforpair{set} returns with:
+%% \digitictr = first digit
+%% \digitiictr = second digit
+%% \numdigitsctr = number of digits (2 for a pair)
+\newcommand*{\checksetforpair}[1]{\bgroup
+ \s@dtemploopcnta\@ne
+ \global\numdigitsctr\z@
+ \global\digitictr\z@
+ \global\digitiictr\z@
+ \loop
+ \ifnum\s@dtemploopcnta<10\relax
+ \numofnuminset{\the\s@dtemploopcnta}{#1}{\s@dtempcnta}
+ \ifnum\s@dtempcnta=\@ne
+ \global\advance\numdigitsctr\@ne
+ \ifcase\numdigitsctr
+ \or \global\digitictr=\s@dtemploopcnta
+ \or \global\digitiictr=\s@dtemploopcnta
+ \else \advance\s@dtemploopcnta 10\relax
+ \fi
+ \fi
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\deleterowpairdigits}
+% \cs{deleterowpairdigits} deletes the pair digits from non-pair cells
+% in a row. The first cell in the row is \cs{s@lcnta}, the cells that
+% contain the two pairs are \cs{s@dncol} and \cs{secondctr}, and the
+% digits are \cs{digitictr} and \cs{digitiictr}.
+% \begin{macrocode}
+%% first row cell is \s@lcnta
+%% first pair cell is \s@dncol, second pair cell is \secondctr
+%% digits are \digitictr and \digitiictr
+\newcommand*{\deleterowpairdigits}{\bgroup
+ \global\pairchangedfalse
+ \s@dtemploopcnta=\s@lcnta
+ \toprangectr=\s@dtemploopcnta \advance\toprangectr 9\relax
+ \loop
+ \ifnum\s@dtemploopcnta<\toprangectr
+ \ifnum\s@dtemploopcnta=\s@dncol
+ \else
+ \ifnum\s@dtemploopcnta=\secondctr
+ \else
+ \deletenumfromset{\the\digitictr}%
+ {\the\useknt{s@lans\the\s@dtemploopcnta}}{\s@dtempcnta}
+ \ifsetchanged
+ \global\useknt{s@lans\the\s@dtemploopcnta}=\s@dtempcnta
+ \global\pairchangedtrue
+ \fi
+ \deletenumfromset{\the\digitiictr}%
+ {\the\useknt{s@lans\the\s@dtemploopcnta}}{\s@dtempcnta}
+ \ifsetchanged
+ \global\useknt{s@lans\the\s@dtemploopcnta}=\s@dtempcnta
+ \global\pairchangedtrue
+ \fi
+ \fi
+ \fi
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reducecolpairs}
+% Loop through the rows and reduce the first pair found.
+% \begin{macrocode}
+%% Loop through the columns, reducing pairs
+\newcommand*{\reducecolpairs}{%
+ \sumctr\z@
+ \s@dncol\@ne
+ \loop
+ \ifnum\s@dncol<10\relax
+ \s@lcnta=\s@dncol
+ \sumcolsets
+ \ifnum\sumctr>\z@
+ \reduceacolpair{\the\s@lcnta}
+ \ifpairchanged
+ \advance\s@dncol 10\relax
+ \fi
+ \fi
+ \advance\s@dncol\@ne
+ \repeat}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reduceacolpair}
+% \cs{reduceacolpair}\marg{colcell} reduces a pair in the column starting
+% with cell \meta{colcell}.
+% \begin{macrocode}
+%% reduceacolpair{col}
+\newcommand*{\reduceacolpair}[1]{\bgroup
+ \s@dnrow=#1\relax
+ \toprangectr=\s@dnrow
+ \advance\toprangectr 73\relax
+ \maxrangectr=\toprangectr
+ \advance\maxrangectr -9\relax
+ \global\sumctr\z@
+ \loop
+ \ifnum\s@dnrow<\maxrangectr
+ \asetctr=\useknt{s@lans\the\s@dnrow}%
+ \ifnum\asetctr>\z@
+ \findcolpair
+ \fi
+ \advance\s@dnrow 9\relax
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\findcolpair}
+% \cs{findcolpair} attempts to find a pair in the current column.
+% \begin{macrocode}
+\newcommand*{\findcolpair}{\bgroup
+ \secondctr=\s@dnrow
+ \advance\secondctr 9\relax
+ \loop
+ \ifnum\secondctr<\toprangectr
+ \ifnum\asetctr=\useknt{s@lans\the\secondctr}
+ \checksetforpair{\the\asetctr}
+ \ifnum\numdigitsctr=\tw@
+%% first row cell is \s@lcnta
+%% first pair cell is \s@dnrow, second pair cell is \secondctr
+%% digits are \digitictr and \digitiictr
+ \deletecolpairdigits
+ \fi
+ \fi
+ \advance\secondctr 9\relax
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\deletecolpairdigits}
+% \cs{deletecolpairdigits} deletes the pair digits from non-pair cells
+% in a column. The first cell in the column is \cs{s@lcnta}, the cells that
+% contain the two pairs are \cs{s@dncol} and \cs{secondctr}, and the
+% digits are \cs{digitictr} and \cs{digitiictr}.
+% \begin{macrocode}
+%% first col cell is \s@lcnta
+%% first pair cell is \s@dnrow, second pair cell is \secondctr
+%% digits are \digitictr and \digitiictr
+\newcommand*{\deletecolpairdigits}{\bgroup
+ \global\pairchangedfalse
+ \s@dtemploopcnta=\s@lcnta
+ \toprangectr=\s@dtemploopcnta \advance\toprangectr 73\relax
+ \loop
+ \ifnum\s@dtemploopcnta<\toprangectr
+ \ifnum\s@dtemploopcnta=\s@dnrow
+ \else
+ \ifnum\s@dtemploopcnta=\secondctr
+ \else
+ \deletenumfromset{\the\digitictr}%
+ {\the\useknt{s@lans\the\s@dtemploopcnta}}{\s@dtempcnta}
+ \ifsetchanged
+ \global\useknt{s@lans\the\s@dtemploopcnta}=\s@dtempcnta
+ \global\pairchangedtrue
+ \fi
+ \deletenumfromset{\the\digitiictr}%
+ {\the\useknt{s@lans\the\s@dtemploopcnta}}{\s@dtempcnta}
+ \ifsetchanged
+ \global\useknt{s@lans\the\s@dtemploopcnta}=\s@dtempcnta
+ \global\pairchangedtrue
+ \fi
+ \fi
+ \fi
+ \advance\s@dtemploopcnta 9\relax
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reduceboxpairs}
+% Loop through the boxes and reduce the first pair found.
+% \begin{macrocode}
+%% Loop through the boxes, reducing pairs
+\newcommand*{\reduceboxpairs}{\bgroup
+ \sumctr\z@
+ \boxctr\@ne
+ \loop
+ \ifnum\boxctr<10\relax
+ \ifcase\boxctr
+ \or \s@lcnta=\@ne
+ \or \s@lcnta=4\relax
+ \or \s@lcnta=7\relax
+ \or \s@lcnta=28\relax
+ \or \s@lcnta=31\relax
+ \or \s@lcnta=34\relax
+ \or \s@lcnta=55\relax
+ \or \s@lcnta=58\relax
+ \or \s@lcnta=61\relax
+ \fi
+ \sumboxsets
+ \ifnum\sumctr>\z@
+ \reduceaboxpair{\the\s@lcnta}
+ \ifpairchanged
+ \advance\boxctr 10\relax
+ \fi
+ \fi
+ \advance\boxctr\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\getnthboxcell}
+% \cs{getnthboxcell}\marg{n}\marg{firstcell}\marg{cnt}. Given the first cell
+% (\meta{firstcell}) in a box and a number, \meta{n}, between 1 and 9, set
+% the \cs{count} \meta{cnt} to the cell number of the \meta{n}th cell in the
+% box.
+% \begin{macrocode}
+%% \getnthboxcell{n}{firstcell}{returnctr}
+\newcommand*{\getnthboxcell}[3]{\bgroup
+ \s@dtempcnta=#2
+ \ifcase#1
+ \or
+ \or \advance\s@dtempcnta 9\relax
+ \or \advance\s@dtempcnta 18\relax
+ \or \advance\s@dtempcnta \@ne
+ \or \advance\s@dtempcnta 10\relax
+ \or \advance\s@dtempcnta 19\relax
+ \or \advance\s@dtempcnta \tw@
+ \or \advance\s@dtempcnta 11\relax
+ \or \advance\s@dtempcnta 20\relax
+ \fi
+ \global #3=\s@dtempcnta
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\reduceaboxpair}
+% \cs{reduceaboxpair}\marg{boxcell} reduces a pair in the box starting
+% with cell \meta{boxcell}.
+% \begin{macrocode}
+%% \reduceaboxpair{startofboxcell}
+\newcommand*{\reduceaboxpair}[1]{\bgroup
+ \s@dtemploopcnta\@ne
+ \toprangectr=\s@dtemploopcnta
+ \advance\toprangectr 9\relax
+ \maxrangectr=\toprangectr
+ \advance\maxrangectr\m@ne
+ \loop
+ \ifnum\s@dtemploopcnta<\maxrangectr
+ \getnthboxcell{\the\s@dtemploopcnta}{#1}{\s@dtempcnta}
+ \asetctr=\useknt{s@lans\the\s@dtempcnta}
+ \ifnum\asetctr>\z@
+ \s@dnrow=\s@dtemploopcnta
+ \findboxpair{#1}
+ \fi
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\findboxpair}
+% \cs{findboxpair} attempts to find a pair in the current box, and then does
+% a pair reduction for the box.
+% \begin{macrocode}
+%% \findboxpair{startofboxcell}
+\newcommand*{\findboxpair}[1]{%
+ \bgroup
+ \secondctr=\s@dtemploopcnta
+ \advance\secondctr\@ne
+ \loop
+ \ifnum\secondctr<\toprangectr
+ \getnthboxcell{\the\secondctr}{#1}{\s@dtempcntb}
+ \ifnum\asetctr=\useknt{s@lans\the\s@dtempcntb}
+ \checksetforpair{\the\asetctr}
+ \ifnum\numdigitsctr=\tw@
+%% first box cell is #1 (=\s@lcnta)
+%% first pair cell is \s@dnrow, second pair cell is \secondctr
+%% digits are \digitictr and \digitiictr
+ \deleteboxpairdigits{#1}
+ \fi
+ \fi
+ \advance\secondctr \@ne
+ \repeat
+ \egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\deleteboxpairdigits}
+% \cs{deleteboxpairdigits}\marg{boxcell} deletes the pair digits from
+% non-pair cells
+% in a box. The first cell in the box is \meta{boxcell}, the cells that
+% contain the two pairs are \cs{s@dnrow} and \cs{secondctr}, and the
+% digits are \cs{digitictr} and \cs{digitiictr}.
+% \begin{macrocode}
+%% first box cell is #1
+%% first pair cell is \s@dnrow, second pair cell is \secondctr
+%% digits are \digitictr and \digitiictr
+\newcommand*{\deleteboxpairdigits}[1]{\bgroup
+ \global\pairchangedfalse
+ \s@dtemploopcnta=\@ne
+ \toprangectr=\s@dtemploopcnta \advance\toprangectr 9\relax
+ \loop
+ \ifnum\s@dtemploopcnta<\toprangectr
+ \ifnum\s@dtemploopcnta=\s@dnrow
+ \else
+ \ifnum\s@dtemploopcnta=\secondctr
+ \else
+ \getnthboxcell{\the\s@dtemploopcnta}{#1}{\s@dtempcntb}
+ \deletenumfromset{\the\digitictr}%
+ {\the\useknt{s@lans\the\s@dtempcntb}}{\s@dtempcnta}
+ \ifsetchanged
+ \global\useknt{s@lans\the\s@dtempcntb}=\s@dtempcnta
+ \global\pairchangedtrue
+ \fi
+ \deletenumfromset{\the\digitiictr}%
+ {\the\useknt{s@lans\the\s@dtempcntb}}{\s@dtempcnta}
+ \ifsetchanged
+ \global\useknt{s@lans\the\s@dtempcntb}=\s@dtempcnta
+ \global\pairchangedtrue
+ \fi
+ \fi
+ \fi
+ \advance\s@dtemploopcnta \@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Checking the solution}
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% check solution %%%%%%%%%%%%%%%%%%%%%%%%%
+
+% \end{macrocode}
+%
+% We have found a solution when all the binary sets are negative.
+% It's less efficient, but probably more useful, to check each
+% row, column, and block (3 times 81 tests instead of 81).
+%
+% \begin{macro}{\checksolution}
+% Check the solution by rows, columns, and boxes.
+% \begin{macrocode}
+\newcommand*{\checksolution}{%
+ \checkrows
+ \checkcols
+ \checkboxes}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\checkrows}
+% Check the row solutions. A row is said to be correct if a solution has
+% been assigned to each cell in the row, thus relying on the assumption
+% that the solver never makes a mistake. The check is not sufficient for
+% a solution obtained in another manner.
+% \begin{macrocode}
+\newcommand*{\checkrows}{%
+ \sumctr\z@
+ \s@dnrow\@ne
+ \loop
+ \ifnum\s@dnrow<10\relax
+ \s@lcnta=\s@dnrow \advance\s@lcnta\m@ne
+ \multiply\s@lcnta 9\relax \advance\s@lcnta\@ne
+ \sumrowsets
+ \ifnum\sumctr=\z@\else
+\typeout{Row \the\s@dnrow\space is incorrect}%
+ Row \the\s@dnrow\space is incorrect. \\
+ \fi
+ \advance\s@dnrow\@ne
+ \repeat}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\checkcols}
+% Check the column solutions.
+% \begin{macrocode}
+\newcommand*{\checkcols}{%
+\bgroup
+ \sumctr\z@
+ \s@dncol\@ne
+ \loop
+ \ifnum\s@dncol<10\relax
+ \s@lcnta=\s@dncol
+ \sumcolsets
+ \ifnum\sumctr=\z@\else
+\typeout{Column \the\s@dncol\space is incorrect}%
+ Column \the\s@dncol\space is incorrect. \\
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\checkboxes}
+% Check the box solutions.
+% \begin{macrocode}
+\newcommand*{\checkboxes}{%
+\bgroup
+ \sumctr\z@
+ \boxctr\@ne
+ \loop
+ \ifnum\boxctr<10\relax
+\ifcase\boxctr
+\or \s@lcnta=\@ne
+\or \s@lcnta=4\relax
+\or \s@lcnta=7\relax
+\or \s@lcnta=28\relax
+\or \s@lcnta=31\relax
+\or \s@lcnta=34\relax
+\or \s@lcnta=55\relax
+\or \s@lcnta=58\relax
+\or \s@lcnta=61\relax
+\fi
+ \sumboxsets
+ \ifnum\sumctr=\z@\else
+\typeout{Box \the\boxctr\space is incorrect}%
+ Box \the\boxctr\space is incorrect. \\
+ \fi
+ \advance\boxctr\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\typesimplestatusX}
+% May be used to display the cuurrent status of the (partial) solution
+% following simple reductions.
+% \begin{macrocode}
+%% typeset the current status of the partial solution
+\newcommand*{\typesimplestatusX}{%
+\par\noindent\begin{minipage}{\linewidth}
+\begin{center}
+Simple reductions stopped (with \the\solcnt\space solutions)\\
+%\footnotesize
+\displaystatus
+\end{center}
+\end{minipage}}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\typelonestatusX}
+% May be used to display the current status of the (partial) solution after a
+% loner reduction.
+% \begin{macrocode}
+%% typeset the current status after loner processing
+\newcommand*{\typelonestatusX}{%
+\par\noindent\begin{minipage}{\linewidth}
+\begin{center}
+Loners processed (with \the\solcnt\space solutions)\\
+%\footnotesize
+\displaystatus
+\end{center}
+\end{minipage}}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\hideprogress}
+% \begin{macro}{\showprogess}
+% Normally the progress towards a solution is not displayed. It will be
+% displayed in the document, though, after the \cs{showprogress} declaration.
+% The \cs{hideprogress} declaration switches off the displays.
+% \begin{macrocode}
+%% For curiosity as to how a solution is developing call the \showprogess
+%% declaration (\hideprogess turns this off).
+\newcommand*{\hideprogress}{%
+ \let\typesimplestatus\relax
+ \let\typelonestatus\relax}
+\newcommand*{\showprogress}{%
+ \let\typesimplestatus\typesimplestatusX
+ \let\typelonestatus\typelonestatusX}
+\hideprogress
+%\showprogress
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%% write solution to a game file %%%%%%%%%%%%%%%
+
+% \end{macrocode}
+%
+% \begin{macro}{\sudsolnfile}
+% \begin{macro}{\writegame}
+% \cs{writegame} writes the (partial) solution to the file \cs{sudsolnfile}
+% (default \file{sud.out}).
+% \begin{macrocode}
+%% write out the solution to game file \sudsolnfile.
+\newcommand*{\sudsolnfile}{sud.out}
+\newcommand*{\writegame}{%
+ \immediate\closeout\s@dwrite
+ \immediate\openout\s@dwrite=\sudsolnfile
+ \s@dnrow\@ne
+ \loop
+ \ifnum\s@dnrow<81\relax
+ \gatherline{\the\s@dnrow}
+ \immediate\write\s@dwrite{\sudaline}
+ \advance\s@dnrow 9\relax
+ \repeat
+ \immediate\closeout\s@dwrite}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\gatherline}
+% \begin{macro}{\sudaline}
+% \cs{gatherline}\marg{rowstartcell} collects the solutions from one
+% row in the grid
+% and converts them into the corresponding characters for one line
+% in a sudoku file, putting the characters into the \cs{sudaline} macro.
+% \begin{macrocode}
+%% \gatherline{colstart}
+%% collect all the characters for one line in a game file
+\newcommand*{\gatherline}[1]{\bgroup
+ \gdef\sudaline{}
+ \s@dncol=#1\relax
+ \toprangectr=\s@dncol
+ \advance\toprangectr 9\relax
+ \loop
+ \ifnum\s@dncol<\toprangectr
+ \s@dtempcnta=\useknt{s@lans\the\s@dncol}
+ \ifnum\s@dtempcnta>\m@ne
+ \g@addto@macro{\sudaline}{.}
+ \else
+ \s@dtempcnta=-\s@dtempcnta
+ \ifcase\s@dtempcnta
+ \or \g@addto@macro{\sudaline}{1}
+ \or \g@addto@macro{\sudaline}{2}
+ \or \g@addto@macro{\sudaline}{3}
+ \or \g@addto@macro{\sudaline}{4}
+ \or \g@addto@macro{\sudaline}{5}
+ \or \g@addto@macro{\sudaline}{6}
+ \or \g@addto@macro{\sudaline}{7}
+ \or \g@addto@macro{\sudaline}{8}
+ \or \g@addto@macro{\sudaline}{9}
+ \else \g@addto@macro{\sudaline}{.}
+ \fi
+ \fi
+ \advance\s@dncol\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macrocode}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% THE END GOAL %%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%% \sudoksolve{<file>} %%%%%%%%%%%%%%%%%%%%%%
+
+% \end{macrocode}
+%
+% \begin{macro}{\sudokusolve}
+% \cs{sudokesolve}\marg{file} reads a sudoku puzzle from the \meta{file}
+% sudoku file, typesets the problem, does its best to solve it.
+% It writes the solution to the \cs{sudsolnfile} file, then reads
+% it back in again and typesets it.
+% \begin{macrocode}
+%% Read in and typeset the problem, solve it, and typeset the answer
+\newcommand{\sudokusolve}[1]{%
+ \begin{center}
+ \sudoku{#1}%
+ \end{center}
+ \getproblem{#1}%
+ \reduceallcells
+ \keepreducing
+ \writegame
+ \noindent\begin{minipage}{\linewidth}
+ THE ANSWER
+ \begin{center}
+ \cluefont\normalsize
+ \cellsize{1.5\baselineskip}
+ \sudoku{\sudsolnfile}
+ \end{center}
+ \end{minipage}}
+
+% \end{macrocode}
+% \end{macro}
+%
+%
+% The end of the package.
+% \begin{macrocode}
+%</solve>
+% \end{macrocode}
+%
+%
+% \subsection{The \Lpack{createsudoku} package}
+%
+% The \Lpack{createsudoku} package lets you automatically generate
+% Sudoku puzzles. The package requires Donald Arseneau's \file{random.tex}
+% and also the \Lpack{solvesudoku} package, which in turn
+% requires the \Lpack{printsudoku} package.
+%
+% \begin{macrocode}
+%<*create>
+\NeedsTeXFormat{LaTeX2e}
+\ProvidesPackage{createsudoku}[2006/02/16 v1.0 create sudoku puzzles]
+\input{random}
+\RequirePackage{solvesudoku}
+
+% \end{macrocode}
+%
+% \begin{macro}{\oldcommentary}
+% \begin{macro}{\commentary}
+% \begin{macro}{\gencommentary}
+% To avoid clutter it's a good
+% idea to switch off \Lpack{solvesudoku}'s commentary. On the other hand
+% it could be useful for this package to provide its own commentary.
+% \begin{macrocode}
+\let\oldcommentary\commentary
+\let\commentary\@gobble
+\newcommand*{\gencommentary}[1]{\typeout{#1}}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\genfile}
+% \begin{macro}{\prevfile}
+% \begin{macro}{\currfile}
+% We need a file to write out the puxzzle to, and we also need two
+% temporary files.
+% \begin{macrocode}
+\newcommand*{\genfile}{gensud.sud}
+\newcommand*{\prevfile}{genprev.sdx}
+\newcommand*{\currfile}{gencurr.sdx}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\randomi}
+% \begin{macro}{\setsudrandom}
+% This sets the seed for the random number generator. The default is
+% setting it to -1, which makes the seed depend on the date and time.
+% \begin{macrocode}
+\randomi\m@ne
+\newcommand*{\setsudrandom}[1]{%
+ \randomi=#1\relax
+ \ifnum\randomi<\@ne\else
+ \nextrandom \nextrandom \nextrandom
+ \typeout{random initialised to #1}%
+ \fi}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\generategrid}
+% \begin{macro}{\printsudresults}
+% \cs{generategrid}\oarg{file} generates a new puzzle. If the sudoko file
+% \meta{file} is specified this is taken for the starting grid, otherwise
+% a default one is used. The starting grid should be a complete solution.
+%
+% The pairs of rows, and pairs of columns, in the starting grid are
+% exchanged in a random fashion (\cs{swaps}) and then the cell solutions
+% are eliminated (\cs{elimclues}) until the puzzle is sufficiently complicated.
+% \begin{macrocode}
+\newcommand*{\generategrid}[1][\@empty]{%
+ \ifx\@empty #1
+ \writestartgrid
+ \getproblem{\prevfile}
+ \else
+ \getproblem{#1}
+ \fi
+ \swaps
+ \elimclues
+ \printsudresults}
+\newcommand*{\printsudresults}{%
+ \sudokusolve{\genfile}%
+ }
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\writestartgrid}
+% Write out an initial fully solved grid to \cs{prevfile}.
+% \begin{macrocode}
+%% the starting data
+\newcommand*{\writestartgrid}{%
+ \immediate\closeout\s@dwrite
+ \immediate\openout\s@dwrite=\prevfile
+ \immediate\write\s@dwrite{123456789}
+ \immediate\write\s@dwrite{456789123}
+ \immediate\write\s@dwrite{789123456}
+ \immediate\write\s@dwrite{234567891}
+ \immediate\write\s@dwrite{567891234}
+ \immediate\write\s@dwrite{891234567}
+ \immediate\write\s@dwrite{345678912}
+ \immediate\write\s@dwrite{678912345}
+ \immediate\write\s@dwrite{912345678}
+ \immediate\closeout\s@dwrite}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\swaps}
+% \cs{swaps} randomly exchanges the contents of pairs of columns and pairs
+% of rows. In order to preserve the number uniqueness constraint for boxes,
+% only pairs of columns/rows that are in the same box may be exchanged.
+% \begin{macrocode}
+\newcommand*{\swaps}{\bgroup
+ \setrannum{\maxrangectr}{36}{48}%
+\gencommentary{number of swaps (36--48) = maxrangectr = \the\maxrangectr}
+ \s@dtemploopcnta\@ne
+ \loop
+ \ifnum\s@dtemploopcnta<\maxrangectr
+ \setrannum{\s@dtempcntb}{1}{18}%
+%%\typeout{\space\space\space swap no \the\s@dtemploopcnta\space is \the\s@dtempcntb}
+ \ifcase\s@dtempcntb
+ \or \swapcolpair{1}{2}%
+ \or \swapcolpair{1}{3}%
+ \or \swapcolpair{2}{3}%
+ \or \swapcolpair{4}{5}%
+ \or \swapcolpair{4}{6}%
+ \or \swapcolpair{5}{6}%
+ \or \swapcolpair{7}{8}%
+ \or \swapcolpair{7}{9}%
+ \or \swapcolpair{8}{9}%
+ \or \swaprowpair{1}{10}%
+ \or \swaprowpair{1}{19}%
+ \or \swaprowpair{10}{19}%
+ \or \swaprowpair{28}{37}%
+ \or \swaprowpair{28}{46}%
+ \or \swaprowpair{37}{46}%
+ \or \swaprowpair{55}{64}%
+ \or \swaprowpair{55}{73}%
+ \or \swaprowpair{64}{73}%
+ \fi
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\swaprowpair}
+% \cs{swaprowpair}\marg{rowstartcell1}\marg{rowstartcell2} swaps the
+% contents of the two rows starting at \meta{rowstartcell1} and
+% \meta{rowstartcell2}.
+% \begin{macrocode}
+%% swap the data in rows starting at #1, and #2
+\newcommand*{\swaprowpair}[2]{\bgroup
+ \s@dncol=#1\relax
+ \s@dcolpos=#2\relax
+ \s@dtemploopcnta\@ne
+ \maxrangectr=10\relax
+ \loop
+ \ifnum\s@dtemploopcnta<\maxrangectr
+ \s@dtempcnta=\useknt{s@lans\the\s@dncol}%
+ \global\useknt{s@lans\the\s@dncol}=\useknt{s@lans\the\s@dcolpos}%
+ \global\useknt{s@lans\the\s@dcolpos}=\s@dtempcnta
+ \advance\s@dncol\@ne
+ \advance\s@dcolpos\@ne
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\swapcolpair}
+% \cs{swapcolpair}\marg{colstartcell1}\marg{colowstartcell2} swaps the
+% contents of the two columns starting at \meta{colstartcell1} and
+% \meta{colstartcell2}.
+% \begin{macrocode}
+%% swap the data in cols starting #1 and #2
+\newcommand*{\swapcolpair}[2]{\bgroup
+ \s@dnrow=#1\relax
+ \s@drowpos=#2\relax
+ \s@dtemploopcnta\@ne
+ \maxrangectr=10\relax
+ \loop
+ \ifnum\s@dtemploopcnta<\maxrangectr
+ \s@dtempcnta=\useknt{s@lans\the\s@dnrow}%
+ \global\useknt{s@lans\the\s@dnrow}=\useknt{s@lans\the\s@drowpos}%
+ \global\useknt{s@lans\the\s@drowpos}=\s@dtempcnta
+ \advance\s@dnrow 9\relax
+ \advance\s@drowpos 9\relax
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimclues}
+% \cs{elimclues} first eliminates a set of clues from the (full) grid, writing
+% the resulting puzzle to the two temporary files \cs{prevfile} and
+% \cs{currfile}. It
+% then eliminates clues one-by-one until the puzzle has been finally
+% generated, the result having been written to the \cs{prevfile},
+% then writing it out to the file \cs{genfile}.
+% \begin{macrocode}
+\newcommand*{\elimclues}{\bgroup
+ \initialelimination
+ \writestate{\prevfile}%
+ \writestate{\currfile}%
+ \elimcluesonebyone
+ \getproblem{\prevfile}
+ \writestate{\genfile}
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimseventeen}
+% \cs{elimseventeen} randomly eliminates the solutions for 17 cells in the
+% grid (apparently if two numbers are completely eliminated as clues in a
+% puzzle, then at best the solution is ambiguous).
+% \begin{macrocode}
+\newcommand*{\elimseventeen}{\bgroup
+ \s@dtemploopcnta\@ne
+ \maxrangectr 18\relax
+ \loop
+ \ifnum\s@dtemploopcnta<\maxrangectr
+ \setrannum{\s@dtempcnta}{1}{81}
+ \global\useknt{s@lans\the\s@dtempcnta}=111111111\relax
+ \advance\s@dtemploopcnta\@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimcross}
+% Eliminate all solutions in column 5 and row 5.
+% \begin{macrocode}
+%% eliminates all clues in column 5 and row 5
+\newcommand*{\elimcross}{\bgroup
+ \s@dtemploopcnta 5\relax
+ \loop
+ \ifnum\s@dtemploopcnta<78\relax% 78 = 5 + 73
+ \global\useknt{s@lans\the\s@dtemploopcnta}=111111111\relax
+ \advance\s@dtemploopcnta 9\relax
+ \repeat
+ \s@dtemploopcnta 37\relax
+ \loop
+ \ifnum\s@dtemploopcnta<46\relax% 46 = 37 + 9
+ \global\useknt{s@lans\the\s@dtemploopcnta}=111111111\relax
+ \advance\s@dtemploopcnta \@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimnum}
+% \cs{elimnum}\marg{num} (\verb?0 < num < 10?) eliminates all
+% instances of the \meta{num} solution from the grid.
+% \begin{macrocode}
+\newcommand*{\elimnum}[1]{\bgroup
+ \s@dtemploopcnta\@ne
+ \loop
+ \ifnum\s@dtemploopcnta<82\relax
+ \ifnum\useknt{s@lans\the\s@dtemploopcnta}=-#1\relax
+ \global\useknt{s@lans\the\s@dtemploopcnta}=111111111\relax
+ \fi
+ \advance\s@dtemploopcnta \@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimcrossandnines}
+% Eliminate all 9's and the solutions in column 5 and row 5.
+% \begin{macrocode}
+\newcommand*{\elimcrossandnines}{\bgroup
+ \elimcross
+ \s@dtemploopcnta\@ne
+ \loop
+ \ifnum\s@dtemploopcnta<82\relax
+ \ifnum\useknt{s@lans\the\s@dtemploopcnta}=-9\relax
+ \global\useknt{s@lans\the\s@dtemploopcnta}=111111111\relax
+ \fi
+ \advance\s@dtemploopcnta \@ne
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimex}
+% Eliminate all solutions on the diagonals of the grid.
+% \begin{macrocode}
+\newcommand*{\elimex}{\bgroup
+ \s@dtemploopcnta\@ne
+ \loop
+ \ifnum\s@dtemploopcnta<82\relax
+ \global\useknt{s@lans\the\s@dtemploopcnta}=111111111\relax
+ \advance\s@dtemploopcnta 10\relax
+ \repeat
+ \s@dtemploopcnta=9\relax
+ \loop
+ \ifnum\s@dtemploopcnta<81\relax
+ \global\useknt{s@lans\the\s@dtemploopcnta}=111111111\relax
+ \advance\s@dtemploopcnta 8\relax
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimcrossandex}
+% Eliminate all solutions in column 5 and row 5 and on the diagonals.
+% \begin{macrocode}
+\newcommand*{\elimcrossandex}{\bgroup
+ \elimcross
+ \elimex
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\elimcrossandexandnines}
+% Eliminate all solutions in column 5 and row 5 and on the diagonals,
+% and all 9's.
+% \begin{macrocode}
+\newcommand*{\elimcrossandexandnines}{\bgroup
+ \elimcross
+ \elimex
+ \elimnum{9}
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\initialelimination}
+% \cs{initialelimination} eliminates an initial set of solutions from the grid.
+% Several predefined sets are provided.
+% \begin{macrocode}
+\let\initialelimination\elimseventeen
+\let\initialelimination\elimcross
+\let\initialelimination\elimcrossandnines
+\let\initialelimination\elimcrossandex
+\let\initialelimination\elimcrossandexandnines
+
+% \end{macrocode}
+% \end{macro}
+%
+%
+% \begin{macro}{\toomanyloops}
+% \begin{macro}{\elimcluesonebyone}
+% Eliminate solutions from the grid one-by-one until the puzzle cannot be
+% solved. Then reinstate the last solution deleted to produce the final puzzle.
+% I'm not sure if this is needed, but just in case the process stops after
+% 81 attempts to remove solutions (highly unlikely but the random number
+% generator could keep producing numbers corresponding to clueless cells).
+%
+% We use the \cs{currfile} and \cs{prevfile} to hold the current state of
+% affairs and the previous state.
+% \begin{macrocode}
+\newcount\toomanyloops
+\newcommand*{\elimcluesonebyone}{\bgroup
+%%%\typeout{***elimcluesonebyone}
+\toomanyloops\z@
+ \s@dtempcntb=81\relax
+ \loop
+ \ifnum\s@dtempcntb>80\relax
+\advance\toomanyloops\@ne
+% \end{macrocode}
+% Read the current puzzle from \cs{currfile} and try to solve it.
+% \begin{macrocode}
+ \getproblem{\currfile}
+ \trysolution
+ \ifnum\solcnt=81\relax % can delete another clue
+% \end{macrocode}
+% The puzzle was solvable so try deleting another clue. Read the (unsolved)
+% puzzle again from \cs{currfile} and write its state to \cs{prevfile}.
+% \begin{macrocode}
+ \getproblem{\currfile}
+ \writestate{\prevfile}
+% \end{macrocode}
+% Now delete a clue, writing the resultant puzzle to \cs{currfile}, and
+% go round the loop again.
+% \begin{macrocode}
+ \deleteaclue
+ \writestate{\currfile}%
+ \s@dtempcntb=81\relax
+ \else % done
+% \end{macrocode}
+% The puzzle was not solvable, and the state before the last clue deletion
+% is in file \cs{prevfile}.
+% \begin{macrocode}
+ \typeout{Solver failed, solcnt = \the\solcnt}
+ \s@dtempcntb=\@ne
+ \fi
+ \ifnum\toomanyloops>80\relax
+ \typeout{Too much looping}
+ \s@dtempcntb=\@ne
+ \fi
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\ifacluenotdeleted}
+% \begin{macro}{\deleteaclue}
+% Keep calling the random number generator until it returns a cell that has
+% a solution,
+% then delete the solution.
+% \begin{macrocode}
+\newif\ifacluenotdeleted
+\newcommand*{\deleteaclue}{\bgroup
+ \acluenotdeletedtrue
+ \loop
+ \ifacluenotdeleted
+ \setrannum{\s@dtempcnta}{1}{81}%
+ \ifnum\useknt{s@lans\the\s@dtempcnta}<\z@% found a clue
+ \gencommentary{Deleting clue for cell \the\s@dtempcnta}%
+ \global\useknt{s@lans\the\s@dtempcnta}=111111111\relax
+ \acluenotdeletedfalse
+ \fi
+ \repeat
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\trysolution}
+% \cs{trysolution} attempts to solve the current puzzle state.
+% \begin{macrocode}
+\newcommand*{\trysolution}{\bgroup
+ \reduceallcells
+ \keepreducing
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\writestate}
+% \cs{writestate}\marg{file} writes the current state (clues and blanks)
+% to the sudoku file \meta{file}.
+% \begin{macrocode}
+%% \writestate{<outputfile>}
+\newcommand*{\writestate}[1]{\bgroup
+ \immediate\closeout\s@dwrite
+ \immediate\openout\s@dwrite=#1
+ \s@dnrow\@ne
+ \loop
+ \ifnum\s@dnrow<81\relax
+ \gatherline{\the\s@dnrow}%
+ \immediate\write\s@dwrite{\sudaline}%
+ \advance\s@dnrow 9\relax
+ \repeat
+ \immediate\closeout\s@dwrite
+\egroup}
+
+% \end{macrocode}
+% \end{macro}
+% The end of the package.
+% \begin{macrocode}
+%</create>
+% \end{macrocode}
+%
+% \section{Example sudoku puzzles}
+%
+% LaTeXing the following file will provide you with a selection of Sudoku
+% puzzles. You can try solving them yourself and/or get Latex to do it for
+% you. The \Lpack{solvesudoku} package is able to solve most, but not all
+% of the puzzles.
+%
+% \begin{macrocode}
+%<*examples>
+\documentclass[twoside]{article}
+\usepackage{comment}
+\usepackage{url}
+\usepackage{printsudoku}
+\newcommand*{\Lpack}[1]{\textsf{#1}}
+\title{Example Sudoku Puzzles}
+\author{Peter Wilson}
+\date{16 February 2006}
+\raggedbottom
+\begin{document}
+\maketitle
+
+ A Sudoku puzzle consists of a 9 by 9 array of squares, some of which have
+numbers in them, the numbers ranging from 1 through 9. The problem is to
+fill in all the squares such that each row, column, and 3 by 3 box includes
+the numbers 1 through 9 with no repetitions.
+
+ This is a collection of some 54 Sudoku puzzles which I have culled
+from various places. The sources include, among others:
+the \emph{Sudoku Solver}~\cite{SSBL} website (labelled SE, SM, SH and SVH),
+\emph{The Daily Telegraph}~\cite{DT2} (labelled TG, TM, and TT),
+\emph{The Seattle Times} (labelled ST),
+and some automatically generated by the \Lpack{createsudoku}
+package~\cite{SUDOKUBUNDLE} (labelled CS).
+
+You can try solving them yourself and/or get
+LaTeX to do it for
+you. The \Lpack{solvesudoku} package~\cite{SUDOKUBUNDLE} is able to solve
+most, but not all of the puzzles. Other LaTeX packages may do better or worse.
+
+ The puzzles are presented in approximately increasing order of difficulty.
+Each source, though, has its own set of categories which don't necessarily
+agree with each other (and sometimes not within one source). I have included
+an indication of the difficulty as stated by the relevant source.
+
+The parameters for the puzzles created via \Lpack{createsudoku} are given in
+the table.
+
+\begin{table}[hbp]
+\centering
+\begin{tabular}{lll} \hline
+Number & Seed & \verb?initialelimination? \\ \hline
+CS1 & 1505263462 & \verb?\elimcrossandexandnines? \\
+CS2 & 1495929734 & \verb?\elimcrossandex? \\
+CS3 & 1487762722 & \verb?\elimcrossandexandnines? \\
+CS4 & 1508763610 & \verb?\elimcrossandex? \\
+CS5 & 839068723 & \verb?\elimseventeen? \\
+CS6 & 833235143 & \verb?\elimcrossandexandnines? \\ \hline
+\end{tabular}
+\end{table}
+
+\cleardoublepage
+
+\cluefont{\LARGE}
+\cellsize{2.25\baselineskip}
+
+\markboth{EASY}{EASY}
+\pagestyle{headings}
+
+\renewcommand*{\puzzlefile}{se5.sud}
+\writepuzzle%
+{.2...5863}{56.2.3.9.}{.3...7251}%
+{..975....}{..6..47.9}{.7..286..}%
+{6.58...7.}{8....1..6}{3.7.6..4.}%
+[SSBL easy 5]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SE5 (easy) \\
+\sudoku{se5.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se10.sud}
+\writepuzzle%
+{..6.497..}{.82.1.6..}{79..8.145}%
+{649.5.27.}{..7.6..5.}{.3..72.96}%
+{.2....81.}{.7..28...}{......5.7}%
+[SSBL easy 10]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SE10 (easy) \\
+\sudoku{se10.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se15.sud}
+\writepuzzle%
+{4.67.39.2}{..16.84..}{.7...4..1}%
+{5...4.21.}{.2.....6.}{.68.7...9}%
+{6..5...9.}{..24.93..}{9.53.17.4}%
+[SSBL easy 15]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SE15 (easy) \\
+\sudoku{se15.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se20.sud}
+\writepuzzle%
+{36.9..5..}{..54.8.2.}{.....78.9}%
+{2....3.68}{.83.9....}{.4.7..2.3}%
+{6.71..3..}{13.8.59.2}{..9.7..56}%
+[SSBL easy 20]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SE20 (easy) \\
+\sudoku{se20.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se25.sud}
+\writepuzzle%
+{....63.5.}{6.5.1.839}{..1...2..}%
+{823...7..}{.5...7...}{.64.9...1}%
+{4.25796.3}{.9.1.65.8}{.1...89.7}%
+[SSBL easy 25]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SE25 (easy) \\
+\sudoku{se25.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se30.sud}
+\writepuzzle%
+{.3.12....}{1.87..4.6}{..98....1}%
+{5....7.3.}{.73.9.2.4}{.92..65..}%
+{.4...8.5.}{3...7...8}{2..4.596.}%
+[SSBL easy 30]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SE30 (easy) \\
+\sudoku{se30.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg5.sud}
+\writepuzzle%
+{.6.1.9.8.}{.19...74.}{2.......1}%
+{..79.26..}{.3.....2.}{..14.35..}%
+{1.......5}{.75...23.}{.9.5.6.7.}%
+[DT2 gentle 5]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TG5 (gentle) \\
+\sudoku{tg5.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg10.sud}
+\writepuzzle%
+{....96..4}{..1.....2}{56...8...}%
+{2.8....9.}{9.63.52.7}{.3....4.6}%
+{...9...58}{7.....9..}{8..45....}%
+[DT2 gentle 10]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TG10 (gentle) \\
+\sudoku{tg10.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg15.sud}
+\writepuzzle%
+{...1.8...}{.57...18.}{98.....26}%
+{..67419..}{.........}{..42536..}%
+{72.....94}{.19...73.}{...3.9...}%
+[DT2 gentle 15]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TG15 (gentle) \\
+\sudoku{tg15.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg20.sud}
+\writepuzzle%
+{...7.9...}{.8.3.6.5.}{7.9...6.8}%
+{..42.18..}{.6.....4.}{..35.41..}%
+{9.2...5.7}{.4.8.7.1.}{...1.2...}%
+[DT2 gentle 20]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TG20 (gentle) \\
+\sudoku{tg20.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg25.sud}
+\writepuzzle%
+{7..4..5..}{.61..5.7.}{.9.7.1..6}%
+{8...27...}{.........}{...34...1}%
+{1..8.2.3.}{.7.1..62.}{..3..9..7}%
+[DT2 gentle 25]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TG25 (gentle) \\
+\sudoku{tg25.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg30.sud}
+\writepuzzle%
+{37.4.....}{9....61.4}{....23...}%
+{.4.1..9..}{.12...79.}{..5..7.4.}%
+{...36....}{4.32....6}{.....9.57}%
+[DT2 gentle 30]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TG30 (gentle) \\
+\sudoku{tg30.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1226.sud}
+\writepuzzle%
+{9....4.31}{7452.....}{.8..674..}%
+{.26.4...5}{5..6.9..8}{4...2.37.}%
+{..759..6.}{.....1823}{21.3....7}%
+[Seattle Times 2005/12/26 1 star]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST1226 (1 star) \\
+\sudoku{st1226.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0206.sud}
+\writepuzzle%
+{17.42...5}{..2.1..96}{849..3...}%
+{....718..}{.25...67.}{..826....}%
+{...5..749}{53..9.1..}{6...48.23}%
+[Seattle Times 2005/02/06 1 star]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0206 (1 star) \\
+\sudoku{st0206.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0213.sud}
+\writepuzzle%
+{.94.2...7}{.36...1.5}{28.35....}%
+{..92...5.}{6.21.49.8}{.7...63..}%
+{....13.46}{1.5...78.}{8...4.29.}%
+[Seattle Times 2006/02/13 1 star]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0213 (1 star) \\
+\sudoku{st0213.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs1.sud}
+\writepuzzle%
+{.46..731.}{2.36.4...}{87.3.1.45}%
+{657...423}{.........}{.81...756}%
+{43.8.6..1}{7..2..5.4}{..25.386.}%
+[CreateSudoku 1 (level 2)]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+CS1 (level 2) \\
+\sudoku{cs1.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs2.sud}
+\writepuzzle%
+{.7.3.265.}{...6..9.7}{64.9.8.2.}%
+{..9...765}{.........}{756...4.2}%
+{29.5...76}{...2.15.3}{..4..7.1.}%
+[CreateSudoku 2 (level 2)]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+CS2 (level 2) \\
+\sudoku{cs2.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs3.sud}
+\writepuzzle%
+{.5.8.71..}{..35.....}{78.2.1.56}%
+{.34...8.1}{.........}{8.1...56.}%
+{.4.7.6.12}{...4.36.8}{.781..34.}%
+[CreateSudoku 3 (level 2)]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+CS3 (level 2) \\
+\sudoku{cs3.sud}
+\end{center}\end{minipage}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% moderate
+
+\clearpage
+\markboth{MODERATE}{MODERATE}
+
+\renewcommand*{\puzzlefile}{sm5.sud}
+\writepuzzle%
+{..76..24.}{.46....9.}{92..85...}%
+{8....29..}{..3...4..}{..49....6}%
+{...73..24}{.5....86.}{.32..67..}%
+[SSBL medium 5]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SM5 (medium) \\
+\sudoku{sm5.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm10.sud}
+\writepuzzle%
+{..57.82..}{4.......6}{.7..6..8.}%
+{52.9.4.31}{.........}{86.1.7.54}%
+{.9..3..6.}{7.......5}{..24.61..}%
+[SSBL medium 10]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SM10 (medium) \\
+\sudoku{sm10.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm15.sud}
+\writepuzzle%
+{85...4..2}{4...2.9..}{...8...7.}%
+{..6.....1}{.4..8..3.}{2.....5..}%
+{.34..7...}{.87.9...6}{6..1...47}%
+[SSBL medium 15]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SM15 (medium) \\
+\sudoku{sm15.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm20.sud}
+\writepuzzle%
+{..34.2.97}{..4....2.}{.7.6....8}%
+{....9....}{.38...47.}{....1....}%
+{4....5.1.}{.5....6..}{72.3.19..}%
+[SSBL medium 20]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SM20 (medium) \\
+\sudoku{sm20.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm25.sud}
+\writepuzzle%
+{...4.79..}{7.6...2..}{..5..83.6}%
+{56..298..}{..8..1...}{.3.7....5}%
+{.......38}{....93...}{.4.5.....}%
+[SSBL medium 25]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SM25 (medium) \\
+\sudoku{sm25.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm30.sud}
+\writepuzzle%
+{..58.....}{....79...}{..461..7.}%
+{.5.3....4}{.23...65.}{9....8.3.}%
+{.3..572..}{...42....}{.....61..}%
+[SSBL medium 30]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SM30 (medium) \\
+\sudoku{sm30.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm35.sud}
+\writepuzzle%
+{5..3.8..6}{..4.5.8..}{2.8...1.5}%
+{..62.74..}{.........}{..94.32..}%
+{9.5...6.4}{..2.1.9..}{1..8.9..2}%
+[DT2 moderate 35]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TM35 (moderate) \\
+\sudoku{tm35.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm40.sud}
+\writepuzzle%
+{...1...92}{9...7..36}{3....2...}%
+{.3....7.9}{.8.9.5.6.}{4.5....8.}%
+{...8....5}{54..2...7}{12...3...}%
+[DT2 moderate 40]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TM40 (moderate) \\
+\sudoku{tm40.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm45.sud}
+\writepuzzle%
+{.1.2.8.3.}{..87.94..}{9.......6}%
+{..9.8.5..}{6.......3}{..3.5.6..}%
+{2.......7}{..73.51..}{.6.4.7.9.}%
+[DT2 moderate 45]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TM45 (moderate) \\
+\sudoku{tm45.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm50.sud}
+\writepuzzle%
+{...9.2..4}{4..3.5...}{3.....7.6}%
+{6..8..3..}{1.3...9.7}{..9..7..2}%
+{9.5.....8}{...2.9..1}{2..7.4...}%
+[DT2 moderate 50]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TM50 (moderate) \\
+\sudoku{tm50.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm55.sud}
+\writepuzzle%
+{7........}{24.1.8...}{.6..72..3}%
+{..4.29.8.}{.7.....6.}{.9.46.7..}%
+{1..68..3.}{...3.7.91}{........6}%
+[DT2 moderate 55]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TM55 (moderate) \\
+\sudoku{tm55.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm60.sud}
+\writepuzzle%
+{724.9.5..}{.5..2...8}{.8.5.7...}%
+{...7..64.}{....8....}{.79..6...}%
+{...8.5.2.}{6...4..8.}{..8.3.174}%
+[DT2 moderate 60]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TM60 (moderate) \\
+\sudoku{tm60.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0914.sud}
+\writepuzzle%
+{.6.29..8.}{..8....3.}{.1..78...}%
+{.217.9..8}{6.......3}{7..6.492.}%
+{...12..4.}{.7....3..}{.5..86.7.}%
+[Seattle Times 2005/09/14 2 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0914 (2 stars) \\
+\sudoku{st0914.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0207.sud}
+\writepuzzle%
+{.......46}{5..8.9.73}{...6..5.1}%
+{.592..1..}{6...1...7}{..3..785.}%
+{2.5..6...}{19.7.5..8}{34.......}%
+[Seattle Times 2005/02/07 2 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0207 (2 stars) \\
+\sudoku{st0207.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs4.sud}
+\writepuzzle%
+{...4.597.}{..67.83.2}{78.1.2.45}%
+{891...75.}{.........}{567...423}%
+{.1...4.67}{..89.15..}{.4....29.}%
+[CreateSudoku 4 (level 8)]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+CS4 (level 4) \\
+\sudoku{cs4.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs5.sud}
+\writepuzzle%
+{...6..978}{..498...2}{.97.21...}%
+{..84.27..}{.7.....23}{3...6...9}%
+{7.6..95..}{...87...1}{.2..4.867}%
+[CreateSudoku 5 (level 4)]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+CS5 (level 4) \\
+\sudoku{cs5.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs6.sud}
+\writepuzzle%
+{.126.4.7.}{6.5..73.2}{.7.3.1.4.}%
+{756...423}{.........}{18......6}%
+{.3.8.6..1}{2.1.....7}{..72...3.}%
+[CreateSudoku 6 (level 4)]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+CS6 (level 4) \\
+\sudoku{cs6.sud}
+\end{center}\end{minipage}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% hard
+
+\clearpage
+\markboth{HARD}{HARD}
+
+\renewcommand*{\puzzlefile}{sh5.sud}
+\writepuzzle%
+{..9..5...}{47...2...}{.836.4.1.}%
+{.15....8.}{...3.7...}{.2....74.}%
+{.4.5.187.}{...7...52}{...2..1..}%
+[SSBL hard 5]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SH5 (hard) \\
+\sudoku{sh5.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh10.sud}
+\writepuzzle%
+{.3.921..5}{15.83....}{.........}%
+{59......4}{37.....81}{6......53}%
+{.........}{....19.26}{9..574.1.}%
+[SSBL hard 10]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SH10 (hard) \\
+\sudoku{sh10.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh15.sud}
+\writepuzzle%
+{2..9.....}{.7..6..59}{...4...61}%
+{7.1..2..4}{....4....}{8..1..9.6}%
+{12...3...}{53..2..7.}{.....9..2}%
+[SSBL hard 15]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SH15 (hard) \\
+\sudoku{sh15.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh20.sud}
+\writepuzzle%
+{.6.2...3.}{9...3...1}{....9.2..}%
+{1..7.....}{.32...46.}{.....4..2}%
+{..7.4....}{2...5...8}{.4...6.5.}%
+[SSBL hard 20]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SH20 (hard) \\
+\sudoku{sh20.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh25.sud}
+\writepuzzle%
+{4....1..8}{..7.3845.}{..24...1.}%
+{28.9.....}{..4...5..}{.....4.86}%
+{.4...92..}{.2134.8..}{9..6....1}%
+[SSBL hard 25]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SH25 (hard) \\
+\sudoku{sh25.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh30.sud}
+\writepuzzle%
+{....5..9.}{.53..78..}{78.4.....}%
+{3....9.2.}{.72...38.}{.1.3....4}%
+{.....1.35}{..58..41.}{.2..3....}%
+[SSBL hard 30]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+SH30 (hard) \\
+\sudoku{sh30.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt100.sud}
+\writepuzzle%
+{...896..7}{..23.5...}{..8...5.1}%
+{15...9...}{3.......9}{...6...54}%
+{8.1...7..}{...9.18..}{6..428...}%
+[DT2 tough 100]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TT100 (tough) \\
+\sudoku{tt100.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt105.sud}
+\writepuzzle%
+{..5.7..46}{6..25....}{.3...6...}%
+{2..7.....}{.78...35.}{.....1..7}%
+{...8...2.}{....97..5}{81..2.9..}%
+[DT2 tough 105]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TT105 (tough) \\
+\sudoku{tt105.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt110.sud}
+\writepuzzle%
+{.79.1....}{.4.5....7}{1..6.....}%
+{9368..1..}{..4...9..}{..7..4632}%
+{.....8..1}{5....6.9.}{....4.82.}%
+[DT2 tough 110]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TT110 (tough) \\
+\sudoku{tt110.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt115.sud}
+\writepuzzle%
+{432.5....}{.....3...}{75.1.....}%
+{..5.823..}{.6.5.1.4.}{..193.2..}%
+{.....6.58}{...3.....}{....2.934}%
+[DT2 tough 115]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TT115 (tough) \\
+\sudoku{tt115.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt120.sud}
+\writepuzzle%
+{..8.1.7..}{.4.67.8..}{..2..461.}%
+{.9....1.8}{.........}{2.1....9.}%
+{.759..4..}{..4.52.6.}{..9.3.5..}%
+[DT2 tough 120]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+TT120 (tough) \\
+\sudoku{tt120.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1130.sud}
+\writepuzzle%
+{8..356...}{5....4.1.}{34.......}%
+{7.156..2.}{.6.....7.}{.2..796.5}%
+{.......32}{.9.4....8}{...682..9}%
+[Seattle Times 2005/11/30 3 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST1130 (3 stars) \\
+\sudoku{st1130.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1207.sud}
+\writepuzzle%
+{...483..6}{.....57.2}{......38.}%
+{..8..16..}{.26.5.17.}{..57..2..}%
+{.82......}{9.18.....}{4..527...}%
+[Seattle Times 2005/12/07 3 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST1207 (3 stars) \\
+\sudoku{st1207.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1209.sud}
+\writepuzzle%
+{...6.....}{.4..8..5.}{.519..2.8}%
+{..729...3}{.9.....1.}{4...679..}%
+{6.8..957.}{.7..2..9.}{.....4...}%
+[Seattle Times 2005/12/09 5 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST1209 (5 stars) \\
+\sudoku{st1209.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1221.sud}
+\writepuzzle%
+{.....392.}{4....5.7.}{29.4...63}%
+{..4....5.}{...2.1...}{.5....3..}%
+{74...2.96}{.6.5....7}{.217.....}%
+[Seattle Times 2005/12/21 3 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST1221 (3 stars) \\
+\sudoku{st1221.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1228.sud}
+\writepuzzle%
+{6..1..5..}{......379}{.942.....}%
+{..5...8.3}{.4.....9.}{9.7...6..}%
+{.....623.}{138......}{..6..8..7}%
+[Seattle Times 2005/12/28 3 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST1228 (3 stars) \\
+\sudoku{st1228.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0126.sud}
+\writepuzzle%
+{..36...7.}{1...352..}{..4......}%
+{..6....29}{7.......4}{32....5..}%
+{......1..}{..824...5}{.4...93..}%
+[Seattle Times 2006/01/26 4 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0126 (4 stars) \\
+\sudoku{st0126.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0127.sud}
+\writepuzzle%
+{25.8.....}{....9.8.2}{9..4.7...}%
+{64.....9.}{.9.1.3.4.}{.7.....21}%
+{...5.4..7}{7.6.8....}{.....1.83}%
+[Seattle Times 2006/01/27 5 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0127 (5 stars) \\
+\sudoku{st0127.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0204.sud}
+\writepuzzle%
+{.5..2.8.6}{.....6..3}{.6..132..}%
+{.7....96.}{4.......1}{.16....3.}%
+{..723..8.}{6..7.....}{2.4.9..7.}%
+[Seattle Times 2006/02/04 6 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0204 (6 stars) \\
+\sudoku{st0204.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0208.sud}
+\writepuzzle%
+{21.9....7}{5.9..421.}{..7......}%
+{..875....}{3.14.95.8}{....361..}%
+{......4..}{.325..9.1}{1....8.25}%
+[Seattle Times 2005/02/08 3 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0208 (3 stars) \\
+\sudoku{st0208.sud}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0209.sud}
+\writepuzzle%
+{..9......}{.523.1...}{8.12.6...}%
+{..4....1.}{97..2..84}{.2....9..}%
+{...8.41.5}{...6.524.}{......8..}%
+[Seattle Times 2005/02/09 4 stars]
+\vfill
+\begin{minipage}{0.95\linewidth}\begin{center}
+ST0209 (4 stars) \\
+\sudoku{st0209.sud}
+\end{center}\end{minipage}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% answers
+
+\clearpage
+\pagestyle{empty}
+\cleardoublepage
+\pagestyle{myheadings}
+\markboth{SOLUTIONS}{SOLUTIONS}
+
+\cluefont{\normalsize}
+\cellsize{1.5\baselineskip}
+
+\renewcommand*{\puzzlefile}{se5.ans}
+\writepuzzle%
+{724195863}{561283497}{938647251}%
+{189756324}{256314789}{473928615}%
+{645839172}{892471536}{317562948}%
+[SSBL easy 5 solution]
+\renewcommand*{\puzzlefile}{se10.ans}
+\writepuzzle%
+{156349782}{482715639}{793286145}%
+{649853271}{217964358}{835172496}%
+{524697813}{371528964}{968431527}%
+[SSBL easy 10 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SE5 (easy solution) \\
+\sudoku{se5.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SE10 (easy solution) \\
+\sudoku{se10.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se15.ans}
+\writepuzzle%
+{456713982}{231698475}{879254631}%
+{597846213}{124935867}{368172549}%
+{643527198}{712489356}{985361724}%
+[SSBL easy 15 solution]
+\renewcommand*{\puzzlefile}{se20.ans}
+\writepuzzle%
+{368912547}{975438621}{412657839}%
+{291543768}{783296414}{546781293}%
+{657129384}{134865972}{829374156}%
+[SSBL easy 20 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SE15 (easy solution) \\
+\sudoku{se15.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SE20 (easy solution) \\
+\sudoku{se20.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{se25.ans}
+\writepuzzle%
+{278963154}{645712839}{931854276}%
+{823641795}{159387462}{764295381}%
+{482579613}{397126548}{516438927}%
+[SSBL easy 25 solution]
+\renewcommand*{\puzzlefile}{se30.ans}
+\writepuzzle%
+{436129875}{128753496}{759864321}%
+{514287639}{673591284}{892346517}%
+{941638752}{365972148}{287415963}%
+[SSBL easy 30 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SE25 (easy solution) \\
+\sudoku{se25.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SE30 (easy solution) \\
+\sudoku{se30.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg5.ans}
+\writepuzzle%
+{764159382}{519238746}{823674951}%
+{457982613}{936715428}{281463597}%
+{142397865}{675841239}{398526174}%
+[DT2 gentle 5 solution]
+\renewcommand*{\puzzlefile}{tg10.ans}
+\writepuzzle%
+{382196574}{491573862}{567248139}%
+{278614395}{946385217}{135729486}%
+{624931758}{753862941}{819457623}%
+[DT2 gentle 10 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TG5 (gentle solution) \\
+\sudoku{tg5.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TG10 (gentle solution) \\
+\sudoku{tg10.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg15.ans}
+\writepuzzle%
+{462198573}{357462189}{981537426}%
+{236741958}{175986342}{894253617}%
+{723615894}{619824735}{548379261}%
+[DT2 gentle 15 solution]
+\renewcommand*{\puzzlefile}{tg20.ans}
+\writepuzzle%
+{256789431}{481326759}{739415628}%
+{594261873}{167938245}{823574196}%
+{912643587}{645897312}{378152964}%
+[DT2 gentle 20 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TG15 (gentle solution) \\
+\sudoku{tg15.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TG20 (gentle solution) \\
+\sudoku{tg20.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tg25.ans}
+\writepuzzle%
+{782463519}{461295378}{395781246}%
+{819527463}{634918752}{527346891}%
+{256872934}{978134625}{243659187}%
+[DT2 gentle 25 solution]
+\renewcommand*{\puzzlefile}{tg30.ans}
+\writepuzzle%
+{376418529}{928756134}{154923678}%
+{749132865}{612584793}{835697241}%
+{597361482}{483275916}{261849357}%
+[DT2 gentle 30 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TG25 (gentle solution) \\
+\sudoku{tg25.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TG30 (gentle solution) \\
+\sudoku{tg30.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1226.ans}
+\writepuzzle%
+{962854731}{745213689}{183967452}%
+{326748915}{571639248}{498125376}%
+{837592164}{659471823}{214386597}%
+[Seattle Times 2005/12/26 1 star solution]
+\renewcommand*{\puzzlefile}{st0206.ans}
+\writepuzzle%
+{176429385}{352817496}{849653217}%
+{463971852}{925384671}{718265934}%
+{281536749}{534792168}{697148523}%
+[Seattle Times 2005/02/06 1 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST1226 (1 star solution) \\
+\sudoku{st1226.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST0206 (1 star solution) \\
+\sudoku{st0206.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0123.ans}
+\writepuzzle%
+{594621837}{736489125}{281357469}%
+{319278654}{652134978}{478596312}%
+{927813546}{145962783}{863745291}%
+[Seattle Times 2006/01/23 1 star solution]
+\renewcommand*{\puzzlefile}{cs1.ans}
+\writepuzzle%
+{546987312}{213654978}{879321645}%
+{657198423}{324765189}{981432756}%
+{435876291}{768219534}{192543867}%
+[CreateSudoku 1 (level 2) solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST0123 (1 star solution) \\
+\sudoku{st0123.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+CS1 (level 2 solution) \\
+\sudoku{cs1.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs2.ans}
+\writepuzzle%
+{978312654}{312645987}{645978321}%
+{189423765}{423756198}{756189432}%
+{291534876}{867291543}{534867219}%
+[CreateSudoku 2 (level 2) solution]
+\renewcommand*{\puzzlefile}{cs3.ans}
+\writepuzzle%
+{456897123}{123564789}{789231456}%
+{234675891}{567918234}{891342567}%
+{345786912}{912453678}{678129345}%
+[CreateSudoku 3 (level 2) solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+CS2 (level 2 solution) \\
+\sudoku{cs2.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+CS3 (level 2 solution) \\
+\sudoku{cs3.ans}
+\end{center}\end{minipage}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% medium
+
+\renewcommand*{\puzzlefile}{sm5.ans}
+\writepuzzle%
+{387691245}{546273198}{921485637}%
+{865342971}{193567482}{274918356}%
+{618739524}{759124863}{432856719}%
+[SSBL medium 5 solution]
+\renewcommand*{\puzzlefile}{sm10.ans}
+\writepuzzle%
+{635748219}{418392576}{279561483}%
+{527984631}{941653827}{863127954}%
+{194835762}{786219345}{352476198}%
+[SSBL medium 10 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SM5 (medium solution) \\
+\sudoku{sm5.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SM10 (medium solution) \\
+\sudoku{sm10.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm15.ans}
+\writepuzzle%
+{853974612}{471326958}{962815473}%
+{396542781}{745681239}{218739564}%
+{134267895}{587493126}{629158347}%
+[SSBL medium 15 solution]
+\renewcommand*{\puzzlefile}{sm20.ans}
+\writepuzzle%
+{863452197}{594178326}{172639548}%
+{617894235}{938526471}{234713869}%
+{489265713}{351947682}{726381954}%
+[SSBL medium 20 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SM15 (medium solution) \\
+\sudoku{sm15.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SM20 (medium solution) \\
+\sudoku{sm20.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sm25.ans}
+\writepuzzle%
+{382467951}{716935284}{495218376}%
+{564329817}{278651493}{139784625}%
+{927146538}{651893742}{843572169}%
+[SSBL medium 25 solution]
+\renewcommand*{\puzzlefile}{sm30.ans}
+\writepuzzle%
+{765834921}{318279465}{294615378}%
+{657392814}{823741659}{941568732}%
+{439157286}{186423597}{572986143}%
+[SSBL medium 30 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SM25 (medium solution) \\
+\sudoku{sm25.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SM30 (medium solution) \\
+\sudoku{sm30.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm35.ans}
+\writepuzzle%
+{591328746}{674951823}{238674195}%
+{356297481}{427185369}{819463257}%
+{985732614}{742516938}{163849572}%
+[DT2 moderate 35 solution]
+\renewcommand*{\puzzlefile}{tm40.ans}
+\writepuzzle%
+{874136592}{952478136}{316592874}%
+{631284759}{287915463}{495367281}%
+{763841925}{548629317}{129753648}%
+[DT2 moderate 40 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TM35 (moderate solution) \\
+\sudoku{tm35.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TM40 (moderate solution) \\
+\sudoku{tm40.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm45.ans}
+\writepuzzle%
+{716248935}{538769421}{924531786}%
+{179683542}{652974813}{483152679}%
+{241896357}{897325164}{365417298}%
+[DT2 moderate 45 solution]
+\renewcommand*{\puzzlefile}{tm50.ans}
+\writepuzzle%
+{751962834}{468375219}{392148756}%
+{627891345}{143526987}{589437162}%
+{975613428}{834259671}{216784593}%
+[DT2 moderate 50 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TM45 (moderate solution) \\
+\sudoku{tm45.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TM50 (moderate solution) \\
+\sudoku{tm50.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tm55.ans}
+\writepuzzle%
+{731946528}{245138679}{968572143}%
+{614729385}{572813964}{893465712}%
+{159684237}{426357891}{387291456}%
+[DT2 moderate 55 solution]
+\renewcommand*{\puzzlefile}{tm60.ans}
+\writepuzzle%
+{734198562}{156324798}{982567431}%
+{813752649}{465983217}{279416853}%
+{341875926}{697241385}{528639174}%
+[DT2 moderate 60 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TM55 (moderate solution) \\
+\sudoku{tm55.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TM60 (moderate solution) \\
+\sudoku{tm60.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0914.ans}
+\writepuzzle%
+{567293184}{298461537}{413578692}%
+{321759468}{649812753}{785634921}%
+{936127845}{872945316}{154386279}%
+[Seattle Times 2005/09/14 2 star solution]
+\renewcommand*{\puzzlefile}{st0207.ans}
+\writepuzzle%
+{872351946}{561849273}{934672581}%
+{759283164}{628514397}{413967852}%
+{285436719}{196725438}{347198625}%
+[Seattle Times 2005/02/07 2 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST0914 (2 star solution) \\
+\sudoku{st0914.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST0207 (2 star solution) \\
+\sudoku{st0207.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs4.ans}
+\writepuzzle%
+{123465978}{456798312}{789132645}%
+{891243756}{234576189}{567819423}%
+{912354867}{678921534}{345687291}%
+[CreateSudoku 4 (level 4) solution]
+\renewcommand*{\puzzlefile}{cs5.ans}
+\writepuzzle%
+{231654978}{564987312}{897321645}%
+{918432756}{675198423}{342765189}%
+{786219534}{453876291}{129543867}%
+[CreateSudoku 5 (level 4) solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+CS4 (level 8 solution) \\
+\sudoku{cs4.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+CS5 (level 8 solution) \\
+\sudoku{cs5.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{cs6.ans}
+\writepuzzle%
+{312654978}{645987312}{978321645}%
+{756198423}{423765189}{189432756}%
+{534876291}{291543867}{867219534}%
+[CreateSudoku 6 (level 4) solution]
+\renewcommand*{\puzzlefile}{sh5.ans}
+\writepuzzle%
+{269175438}{471832965}{583694217}%
+{715426389}{894317526}{326958741}%
+{942561873}{138749652}{657283194}%
+[SSBL hard 5 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+CS6 (level 4 solution) \\
+\sudoku{cs6.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SH5 (hard solution) \\
+\sudoku{sh5.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh10.ans}
+\writepuzzle%
+{437921865}{156837492}{289456137}%
+{598163274}{374295681}{621748953}%
+{713682549}{845319726}{962574318}%
+[SSBL hard 10 solution]
+\renewcommand*{\puzzlefile}{sh15.ans}
+\writepuzzle%
+{216935847}{478261359}{395478261}%
+{761392584}{952846713}{843157926}%
+{124783695}{539624178}{687519432}%
+[SSBL hard 15 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SH10 (hard solution) \\
+\sudoku{sh10.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SH15 (hard solution) \\
+\sudoku{sh15.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh20.ans}
+\writepuzzle%
+{468271935}{925438671}{713695284}%
+{154762893}{832519467}{679384512}%
+{587943126}{296157348}{341826759}%
+[SSBL hard 20 solution]
+\renewcommand*{\puzzlefile}{sh25.ans}
+\writepuzzle%
+{439561728}{167238459}{852497613}%
+{286953174}{794816532}{513724986}%
+{348179265}{621345897}{975682341}%
+[SSBL hard 25 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SH20 (hard solution) \\
+\sudoku{sh20.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+SH25 (hard solution) \\
+\sudoku{sh25.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{sh30.ans}
+\writepuzzle%
+{461258793}{253917846}{789463152}%
+{346789521}{572146389}{918325674}%
+{894671235}{635892417}{127534968}%
+[SSBL hard 30 solution]
+\renewcommand*{\puzzlefile}{tt100.ans}
+\writepuzzle%
+{513896427}{742315698}{968742531}%
+{154289376}{376154289}{289637154}%
+{891563742}{425971863}{637428915}%
+[DT2 tough 100 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+SH30 (hard solution) \\
+\sudoku{sh30.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TT100 (tough solution) \\
+\sudoku{tt100.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt105.ans}
+\writepuzzle%
+{925378146}{681254793}{734916582}%
+{256739418}{178462359}{349581267}%
+{597843621}{462197835}{813625974}%
+[DT2 tough 105 solution]
+\renewcommand*{\puzzlefile}{tt110.ans}
+\writepuzzle%
+{379412586}{648539217}{125687349}%
+{936825174}{214763958}{857194632}%
+{492358761}{581276493}{763941825}%
+[DT2 tough 110 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TT105 (tough solution) \\
+\sudoku{tt105.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TT110 (tough solution) \\
+\sudoku{tt110.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{tt115.ans}
+\writepuzzle%
+{432758196}{196243587}{758169423}%
+{945682371}{263571849}{871934265}%
+{329416758}{584397612}{617825934}%
+[DT2 tough 115 solution]
+\renewcommand*{\puzzlefile}{tt120.ans}
+\writepuzzle%
+{968215734}{143679852}{752384619}%
+{496523178}{537198246}{281746395}%
+{875961423}{314852967}{629437581}%
+[DT2 tough 120 solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+TT115 (tough solution) \\
+\sudoku{tt115.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+TT120 (tough solution) \\
+\sudoku{tt120.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1130.ans}
+\writepuzzle%
+{819356247}{576924813}{342817596}%
+{781563924}{965248371}{423179685}%
+{658791432}{297435168}{134682759}
+[Seattle Times 2005/11/30 3 star solution]
+\renewcommand*{\puzzlefile}{st1207.ans}
+\writepuzzle%
+{217483956}{834695712}{659172384}%
+{798231645}{326954178}{145768239}%
+{582319467}{971846523}{463527891}%
+[Seattle Times 2005/12/07 3 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST1130 (3 star solution) \\
+\sudoku{st1130.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST1207 (3 star solution) \\
+\sudoku{st1207.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1209.ans}
+\writepuzzle%
+{839652147}{246781359}{751943268}%
+{167295483}{592438716}{483167925}%
+{628319574}{374526891}{915874632}%
+[Seattle Times 2005/12/09 5 star solution]
+\renewcommand*{\puzzlefile}{st1221.ans}
+\writepuzzle%
+{517863924}{436925178}{298417563}%
+{174389652}{683251749}{952674381}%
+{745132896}{369548217}{821796435}%
+[Seattle Times 2005/12/21 3 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST1209 (5 star solution) \\
+\sudoku{st1209.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST1221 (3 star solution) \\
+\sudoku{st1221.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st1228.ans}
+\writepuzzle%
+{673189524}{812654379}{594273186}%
+{265791843}{341865792}{987342651}%
+{795416238}{138927465}{426538917}%
+[Seattle Times 2005/12/28 3 star solution]
+\renewcommand*{\puzzlefile}{st0126.ans}
+\writepuzzle%
+{253698471}{197435286}{864127953}%
+{416573829}{785912634}{329864517}%
+{972356148}{638241795}{541789362}%
+[Seattle Times 2006/01/26 4 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST1228 (3 star solution) \\
+\sudoku{st1228.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST0126 (4 star solution) \\
+\sudoku{st0126.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0127.ans}
+\writepuzzle%
+{253816479}{467395812}{918427536}%
+{641752398}{892163745}{375948621}%
+{189534267}{736289154}{524671983}%
+[Seattle Times 2006/01/27 5 star solution]
+\renewcommand*{\puzzlefile}{st0204.ans}
+\writepuzzle%
+{153427896}{742986513}{869513247}%
+{375142968}{428369751}{916875432}%
+{597321684}{681754329}{234698175}%
+[Seattle Times 2006/02/04 6 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST0127 (5 star solution) \\
+\sudoku{st0127.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST0204 (6 star solution) \\
+\sudoku{st0204.ans}
+\end{center}\end{minipage}
+
+\renewcommand*{\puzzlefile}{st0208.ans}
+\writepuzzle%
+{213985647}{589674213}{647213859}%
+{928751364}{361429578}{754836192}%
+{875192436}{432567981}{196348725}%
+[Seattle Times 2005/02/08 3 star solution]
+\renewcommand*{\puzzlefile}{st0209.ans}
+\writepuzzle%
+{639587421}{752341698}{841296753}%
+{584769312}{976123584}{123458976}%
+{297834165}{318675249}{465912837}%
+[Seattle Times 2005/02/09 4 star solution]
+\vfill
+\noindent\begin{minipage}{0.47\linewidth}\begin{center}
+ST0208 (3 star solution) \\
+\sudoku{st0208.ans}
+\end{center}\end{minipage}
+\hfill
+\begin{minipage}{0.47\linewidth}\begin{center}
+ST0209 (4 star solution) \\
+\sudoku{st0209.ans}
+\end{center}\end{minipage}
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% bibliography
+\cleardoublepage
+
+\bibliographystyle{alpha}
+\begingroup
+\raggedright
+\begin{thebibliography}{GMSN94A}
+
+\bibitem[Mep05]{DT2}
+Michael Mepham.
+\emph{The Daily Telegraph Sudoku 2}.
+\newblock Pan Books, 2005.
+\newblock ISBN 0-330-44203-3.
+
+\bibitem[Wil06]{SUDOKUBUNDLE}
+Peter Wilson.
+\emph{The sudoku bundle for displaying, solving and generating
+ Sudoku puzzles}.
+\newblock February 2006.
+\newblock (Available from CTAN in \url{macros/latex/contrib/sudokubundle}).
+
+\bibitem[SOL]{SOL}
+\emph{Sudoku Online: Home of the Sudokulist}.
+\newblock \url{http://www.sudoku.org.uk}
+
+\bibitem[SSBL]{SSBL}
+\emph{Sudoku Solver ... by logic}.
+\newblock \url{http://www.sudokusolver.co.uk}
+
+\end{thebibliography}
+\endgroup
+
+\end{document}
+
+%</examples>
+% \end{macrocode}
+%
+% \Finale
+%
+%
+\endinput
+
+%% \CharacterTable
+%% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+%% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+%% Digits \0\1\2\3\4\5\6\7\8\9
+%% Exclamation \! Double quote \" Hash (number) \#
+%% Dollar \$ Percent \% Ampersand \&
+%% Acute accent \' Left paren \( Right paren \)
+%% Asterisk \* Plus \+ Comma \,
+%% Minus \- Point \. Solidus \/
+%% Colon \: Semicolon \; Less than \<
+%% Equals \= Greater than \> Question mark \?
+%% Commercial at \@ Left bracket \[ Backslash \\
+%% Right bracket \] Circumflex \^ Underscore \_
+%% Grave accent \` Left brace \{ Vertical bar \|
+%% Right brace \} Tilde \~}
+
+
diff --git a/Master/texmf-dist/source/latex/sudokubundle/sudokubundle.ins b/Master/texmf-dist/source/latex/sudokubundle/sudokubundle.ins
new file mode 100644
index 00000000000..6c0fbbd7786
--- /dev/null
+++ b/Master/texmf-dist/source/latex/sudokubundle/sudokubundle.ins
@@ -0,0 +1,83 @@
+%% sudokubundle.ins
+%% Author: Peter Wilson (herries dot press at earthlink dot net
+%% Herries Press
+%% Copyright 2006 Peter R. Wilson
+%%
+%% This work may be distributed and/or modified under the
+%% conditions of the LaTeX Project Public License, either
+%% version 1.3 of this license or (at your option) any
+%% later version.
+%% The latest version of the license is in
+%% http://www.latex-project.org/lppl.txt
+%% and version 1.3 or later is part of all distributions of
+%% LaTeX version 2003/06/01 or later.
+%%
+%% This work has the LPPL maintenance status "author-maintained".
+%%
+%% This work consists of the files listed in the README file.
+%%
+%% This file will generate fast loadable files and documentation
+%% driver files from the doc files in this work when run through
+%% LaTeX.
+%%
+%% --------------- start of docstrip commands ------------------
+%%
+\def\batchfile{sudokubundle.ins}
+\input docstrip.tex
+\preamble
+
+-----------------------------------------------------------------
+ Author: Peter Wilson (herries dot press at earthlink dot net)
+ Herries Press
+ Copyright 2006 Peter R. Wilson
+
+ This work may be distributed and/or modified under the
+ conditions of the LaTeX Project Public License, either
+ version 1.3 of this license or (at your option) any
+ later version.
+ The latest version of the license is in
+ http://www.latex-project.org/lppl.txt
+ and version 1.3 or later is part of all distributions of
+ LaTeX version 2003/06/01 or later.
+
+ This work has the LPPL maintenance status "author-maintained".
+
+ This work consists of the files listed in the README file.
+-----------------------------------------------------------------
+
+\endpreamble
+
+\keepsilent
+
+%%% \Msg{*** Generating the driver file ***}
+%%% \generateFile{sudokubundle.drv}{t}{\from{sudokubundle.dtx}{driver}}
+
+\Msg{*** Generating the LaTeX2e package files ***}
+
+\generateFile{printsudoku.sty}{t}{\from{sudokubundle.dtx}{print}}
+\generateFile{solvesudoku.sty}{t}{\from{sudokubundle.dtx}{solve}}
+\generateFile{createsudoku.sty}{t}{\from{sudokubundle.dtx}{create}}
+\generateFile{somesudoku.tex}{t}{\from{sudokubundle.dtx}{examples}}
+
+\Msg{***********************************************************}
+\Msg{*}
+\Msg{* To finish the installation you have to move the following}
+\Msg{* file(s) into a directory searched by TeX. For more information}
+\Msg{* see the FAQ on CTAN at /help/uk-tex-faq.}
+\Msg{*}
+\Msg{* \space\space printsudoku.sty}
+\Msg{* \space\space solvesudoku.sty}
+\Msg{* \space\space createsudoku.sty}
+\Msg{*}
+\Msg{*}
+\Msg{* To produce the documentation run the files ending with}
+\Msg{* `.dtx' through LaTeX.}
+\Msg{* For an index, process any name.idx file by:}
+\Msg{* \space\space\space\space makeindex -s gind.ist name}
+\Msg{* For a list of changes, process any name.glo file by:}
+\Msg{* \space\space\space\space makeindex -s gglo.ist -o name.gls name.glo}
+\Msg{*}
+\Msg{* Happy TeXing}
+\Msg{***********************************************************}
+
+\endinput
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 22:47:19 +0000