Re: [FWP] Love & Hate shenanigans

[Sven Neuhaus <sn@neopoly.com>]

On Thu, Mar 29, 2001 at 01:19:19PM +0300, Ilmari Karonen wrote:
> However, there are some nice ways in which ASCII characters behave in
> XOR operations.  In particular, XORing a letter with a space flips the
> case of that letter, so ("foo" ^ " ") eq "Foo".

I'm wondering if this can be done substantially faster and wether it 
will find anything in my /usr/dict/words. Right now it checks 10 in ~6 
seconds on a p2-400 on a dict file with 45402 words.

Also interesting: Converting the large array to a hash is very slow with
map and fast with foreach:

===================8<=========================8<=====================
#!/usr/bin/perl
use integer;

chop(@words = <>); print "read\n";
@words = map { lc } @words; print "lc\n";
@Words = map { uc } @words; print "uc\n";

keys %words = 45402;
#%Words = map { $_ => 1 } @Words; # takes ages?!
foreach (@Words) { $Words{$_} = 1 } # fast
print "hash\n";

print "Go!\n";
$|=1;
for($i=0; $i < @words; $i++) {
    $w1 = $words[$i];
    $W1 = $Words[$i];
    print "$w1                  \r";
    for($j=$i; $j < @words; $j++) {
        $w2 = $words[$j];
        $W2 = $Words[$j];
        print "\n$w1 ^ $w2" . ($w1^$w2)."\n" if exists $Words{uc($w1^$w2)};
        print "\n$W1 ^ $w2" . ($W1^$w2)."\n" if exists $Words{uc($W1^$w2)};
        print "\n$w1 ^ $W2" . ($w1^$W2)."\n" if exists $Words{uc($w1^$W2)};
        print "\n$W1 ^ $W2" . ($W1^$W2)."\n" if exists $Words{uc($W1^$W2)};
    }
}
===================8<=========================8<=====================

-Sven
-- 
Be cheerful while you are alive.
		-- Phathotep, 24th Century B.C.

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