find and print

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