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/*****
* treedef.asy
* Andy Hammerlindl 2003/10/25
*
* Implements a dynamic binary search tree.
*****/
struct tree
{
tree left = null;
tree right = null;
int key = 0;
int value = 0;
}
tree newtree()
{
return null;
}
tree add(tree t, int key, int value)
{
if (t == null) {
tree tt;
tt.key = key; tt.value = value;
return tt;
}
else if (key == t.key) {
return t;
}
else if (key < t.key) {
tree tt;
tt.left = add(t.left, key, value);
tt.key = t.key;
tt.value = t.value;
tt.right = t.right;
return tt;
}
else {
tree tt;
tt.left = t.left;
tt.key = t.key;
tt.value = t.value;
tt.right = add(t.right, key, value);
return tt;
}
}
bool contains(tree t, int key)
{
if (t == null)
return false;
else if (key == t.key)
return true;
else if (key < t.key)
return contains(t.left, key);
else
return contains(t.right, key);
}
int lookup(tree t, int key)
{
if (t == null)
return 0;
else if (key == t.key)
return t.value;
else if (key < t.key)
return lookup(t.left, key);
else
return lookup(t.right, key);
}
void write(file out=stdout, tree t)
{
if (t != null) {
if(t.left != null) {
write(out,t.left);
}
write(out,t.key);
write(out,"->");
write(out,t.value,endl);
if (t.right != null) {
write(out,t.right);
}
}
}
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