#! perl -slw use strict; my @words = do{ local @ARGV = 'words.txt'; <> }; chomp @words; my $all = join ' ', @words; my $start = time; my $n = 0; for my $i ( @words ) { for my $j ( $all =~ m[ ([^ ]*$i[^ ]*) ]g ) { next if $j eq $i or $j eq "${i}s" or $j eq "${i}'s"; # print "$j contains $i"; } } printf STDERR "Took %d seconds for %d words\n", time() - $start, scalar @words;