The following solution only passes once through the dictionary, and doesn't need an additional pass through
the hash. It also stores less in the hash. It takes advantage
of the fact that the dictionary is sorted, and that a word
of the form Xm sorts before Xrn.
#!/usr/bin/perl
use strict;
use warnings;
my $file = "/usr/share/dict/words";
open my $fh => $file or die;
my %seen;
while (<$fh>) {
chomp;
if (/m$/) {
$seen {+lc} ++;
next;
}
elsif (/rn$/) {
if ($seen {lc "$`m"}) {
print "$`m/$_\n";
}
next;
}
}
__END__
bum/burn
chum/churn
dam/darn
hom/horn
modem/modern
stem/stern
tom/torn
Abigail | [reply]
[d/l] |
| [reply] |
As for correctness, did you try running mine? Yours gives only five results on my dictionary as well. If mine isn't capturing everything, I can't figure out why. Help?
As for the differing results we got, note that I included the version of /usr/share/dict/words that I used; mine, for some wacky reason, doesn't contain the words 'yam', 'mom' or 'tom'. It does contain 'Tom', (not 'Mom' or 'Yam') but I was looking for improper nouns. Good catch on the case issue, though I notice your example has it as well. Eh, it's not a hard fix.
The bit about using hashes is quite nifty. I was considering breaking it down to one pass, but couldn't figure out how to get it to be order-agnostic. (I was still using a single pointer in the list.) The hash neatly sidesteps all of that. Cool!
I should learn to use non-capturing parentheses when I'm not snagging the output, too.
Thanks!
| [reply]
[d/l] |
To fix up the case sensitivity issues, we can do something like what I did here. A new rewrite of the code, will display all matches (2 or more), that follow the 'rn'/'m' rule. For example, 'stern', 'Stern', and 'stem' are all in my dictionary. S it displays all three :)
#!/usr/bin/perl -w
use strict;
open my $dict, '<', '/usr/share/dict/words'
or die "open failed: $!";
my %words;
while (<$dict>) {
chomp $_;
my $index = lc $_;
next unless $index =~ s/(m|rn)\z//i;
push @{$words{$index}{$1}}, $_;
}
while (my ($index, $word) = each %words) {
print join(" / ", @{$word->{rn}}, @{$word->{m}}), "\n"
if $word->{rn} && $word->{m};
}
| [reply]
[d/l] |