in reply to (Golf) Cryptographer's Tool #1

My original best was 63 characters: 
sub canonical {
my(@a,$i,%c,$c)=pop=~/./g;$c.=$c{$_}||=$a[$i++]for pop=~/./g;$c
}

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(which is strict compliant, but only because at that point it wasn't any shorter being non-strict compliant. :)

However, here's a 46 character solution building off of btrott's solutions: 

sub canonical {
($_,$a,%h)=@_;s!.!$h{$&}||=($a=~/./g,$&)!ge;$_
}

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Can be called multiple times, of course, as in the example.

 

Update: Well, tilly's been mumbling something about following the spec :) , so here's a solution that accepts any ASCII character (including zero and linefeed) in the word or the alphabet: 
sub canonical {
($_,$a,%h)=@_;s!.!{$h{$&}=~s+^\z+$a=~/./gs,$&+ge}$h{$&}!gse;$_
}

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At 62, it actually beats my original solution by 1 character!

Replies are listed 'Best First'.
Re: Re: (Golf) Cryptographer's Tool #1
by MeowChow (Vicar) on Jun 20, 2001 at 03:27 UTC
    Following the spec at 61: 
    sub c {
($_,$a,%h)=@_;join'',map{substr$a,($h{$_}||=keys%h)-1,1}/./gs
}

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    ... and also in spiritus strictus at 62: 
    sub c {
my%h;join'',map{substr$_[1],($h{$_}||=keys%h)-1,1}$_[0]=~/./gs
}

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       MeowChow                                   
               s aamecha.s a..a\u$&owag.print
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[d/l]
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      Oo, nice! And with inspiration once again from btrott's substitution approach: 
      sub canonical {
($_,$a,%h)=@_;s/./substr"a$a",$h{$&}||=keys%h,1/gse;$_
}

      [download]
      Back down to 54!
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[d/l]
Re: Re: (Golf) Cryptographer's Tool #1
by srawls (Friar) on Jun 20, 2001 at 02:17 UTC
    That doesn't work when 0 is in the 'alphabet.' Here's a modified solution that handles 0 properly, which is only 8 more char than yours: It adds the null character to each string, which shouldn't print on most machines (it does on my dos, not on my unix). 
    sub c { 
($_,$a)=@_;s!.!$h{$&}||=($a=~/./g,"$&\0")!ge;y/\0//;$_
}

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    Update:Fixed code as per chipmunk's comment. It's 54 chars now.

    The 15 year old, freshman programmer,
    Stephen Rawls

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[d/l]
      Adding extra characters to the result is not a valid solution. They may be invisible when you print them out, but they're still there.
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      nice, srawls... here it is down to 51: 
      sub c{
($_,$a)=@_;s!.!chr($h{$&}||=($a=~/./g,ord$&))!ge;$_
#23456789_123456789_123456789_123456789_123456789_1
}

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      It doesn't work with null either, but as i read it, thats fine.

      update: oops, here's one that resets %h and is reusable, as per the given example, at 54:
      sub c{
($_,$a,%h)=@_;s!.!chr($h{$&}||=($a=~/./g,ord$&))!ge;$_
#23456789_123456789_123456789_123456789_123456789_1234
}

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      --sean
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[d/l]
[select]
      The fix fails if a null character is present in the alphabet. 
         MeowChow                                   
               s aamecha.s a..a\u$&owag.print
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        Yes it does, but the this is straight from the specification:

        Given: a word, and an 'alphabet' string (and to be exact about this latter part, each character in the word and the alphabet can be represented in 7 bits, eg the printable ASCII set).

        The 15 year old, freshman programmer,
        Stephen Rawls

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