in reply to Re^2: A Better Word Morph Builder
in thread A Better Word Morph Builder

Ieronim,
I give. While I understand your admittedly fast code - it is extremely hard to follow. The cleanest code I could come up with using a bi-directional BFS is as fast as your transform() before following my recommendation. That is to say, it is about half as fast as your current version:
use constant SRC => 0; use constant TGT => 1; sub find_path2 { my ($src, $tgt, $list) = @_; my (@src_work, @tgt_work, %path); for my $dir (SRC, TGT) { my ($word, $work) = $dir == SRC ? ($src, \@src_work) : ($tgt, +\@tgt_work); $path{$word}[$dir] = -1; for (@{$list->{$word}}) { push @$work, $_; $path{$_}[$dir] = $word; } } while (1) { for my $dir (SRC, TGT) { my @next; my $work = $dir == SRC ? \@src_work : \@tgt_work; for my $word (@$work) { return build_path(\%path, $word) if $path{$word}[abs($ +dir - 1)]; for (@{$list->{$word}}) { next if $path{$_}[$dir]; push @next, $_; $path{$_}[$dir] = $word; } } @$work = @next; } return 'Path not found' if ! @src_work && ! @tgt_work; } } sub build_path { my ($tree, $node) = @_; my $path = "-$node"; for my $dir (SRC, TGT) { my $word = $tree->{$node}[$dir]; while ($word ne '-1') { $path = $dir == SRC ? "-$word$path" : "$path-$word"; $word = $tree->{$word}[$dir]; } } return substr($path, 1); }
Update (2006-07-03): Simply moving return build_path(\%path, $word) if $path{$word}[abs($dir - 1)]; to the inner most for loop and s/word/_/ brings the performance much closer. See the update in this node for an explanation why.

Cheers - L~R