Find the longest common starting substring in a set of strings [closed]

Answer 1

This is probably not the most concise solution (depends if you already have a library for this), but one elegant method is to use a trie. I use tries for implementing tab completion in my Scheme interpreter:

http://github.com/jcoglan/heist/blob/master/lib/trie.rb

For example:

tree = Trie.new
%w[interspecies interstelar interstate].each { |s| tree[s] = true }
tree.longest_prefix('')
#=> "inters"

I also use them for matching channel names with wildcards for the Bayeux protocol; see these:

http://github.com/jcoglan/faye/blob/master/client/channel.js

http://github.com/jcoglan/faye/blob/master/lib/faye/channel.rb