gistfile1.rb

    # Use a covering technique to cover first blacks, then whites
    # At each step, anything covered is acccounted for.
    # Anything uncovered at the end is just plain wrong
    def guess(guess)
      covered_result = @secret_code.dup
      guess.each_with_index do |color, i|
        covered_result[i] = 'b' if @secret_code[i] == color
      end
      
      guess.each_with_index do |color, i|
        match = covered_result.index(color)
        covered_result[match] = 'w' if match
      end
      
      print_result(covered_result)
    end
    
    private
    def print_result(result)
      @messenger.puts result.select {|c| c =~ /[bw]/}.sort.join
    end