find and print

#!/usr/bin/env ruby
input = open('input.txt').to_a
open('list.txt').map {|e|
  e.strip!
  ([e] + input.select {|li| li.include? e }.map {|li| li.split[0] })
  .join "\t"
}.join("\n").tap {|e| open('output.txt', 'w') {|f| f.puts e } }