From: Eric Promislow <eric.promislow@...>
Date: 2007-08-04T07:34:59+09:00
Subject: Re: Determining the common prefix for several strings

The obligatory solution using zip...

# data contains a list of strings
aa = data.map{ |x| x.split(//)}
bz = aa[0].zip(*(aa[1 .. -1])).map{ |x| x.join("")}
target = bz.index( bz.find{ |x| x.squeeze.size != 1})
answer = (target.nil? ? aa[0] :
          target >= 1 ? aa[0][0 .. target - 1] :
          []).join("")

- Eric