From: Xavier Noria <fxn@...>
Date: 2007-08-03T22:39:55+09:00
Subject: Re: Determining the common prefix for several strings

El Aug 3, 2007, a las 1:35 PM, Xavier Noria escribi�:

>   prefix = ''
>   min, max = items.sort.values_at(0, -1)
>   min.split(//).each_with_index do |c, i|
>     break if c != max[i, 1]
>     prefix << c
>   end
>   puts prefix

Yet another iteration: the prefix can be extracted with a regexp,  
it's shorter although perhaps more obscure:

   min, max = items.sort.values_at(0, -1)
   puts min+max =~ /(.).{#{min.length-1}}(?!\1)/m ? $` : min

I don't like the ternary and the fact that we look for the first  
mismatch instead of extracting directly the prefix in one shot.

-- fxn