From: Eric Young <eay_nospam@...>
Date: 2006-03-12T15:58:43+09:00
Subject: Re: Help me understand why the Ruby block is slower than wit

Benjohn Barnes wrote:
> 
> On 11 Mar 2006, at 02:13, George Ogata wrote:
> 
>> Another speedup:  replace:
>>
>>   w.split(//).uniq.size == 11
>>
>> with:
>>
>>   w !~ /(.).*\1/
> 
> !? :) How on earth does that work? Every time I think I've sort of got 
> the hang of regexp, they spring something new on me.
> 
> I was also going to ask why everyone was doing "split( // )" instead of 
> "split( '' )"?
> 
> - oooh, coffee's ready...
> 
> Cheers,
>     Benjohn


I was going to ask why everyone is not doing
  w.unpack("C*").uniq! == nil
which seems faster than split(//) but slower than /(.).*\1/

3.2s      puts l if l !~ /(.).*\1/
3.6s      puts l unless l.unpack("C*").uniq!
7.3s      puts l if l.split(//).uniq.size == 11

perhaps I deal with C code to much, but unpack seems a better String -> 
array mechanism.

eric (rather new to ruby)
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