Parity Problem Generator

ppg.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

# ppg.rb : Parity Problem Generator
#   by takehikom (http://d.hatena.ne.jp/takehikom/)

# Usage:
#   ruby ppg.rb
#   ruby ppg.rb 3

# 遊び方
#   どの行・どの列も，すべて偶数または奇数となるよう，
#   反転させるべき場所（1箇所だけ）を見つけてください．
#   偶数か奇数かは，問題ごとにランダムです．
#   引数なしで実行した場合，最初に問題が表示されます．Enterのみを押せば
#   解答，そして次の問題に移り（無限ループ），qとEnterを押せば終了します．
#   引数（整数値）をつけて実行した場合，その数だけ，問題と解答を出力します．

module ParityProblem
  class Board
    def initialize(h = nil)
      if h.nil?
        h = {
          :width => 6 + rand(3),
          :height => 4 + rand(3),
          :even => rand(2) == 0,
        }
      end
      @width = h[:width] || 6
      @height = h[:height] || 6
      @even = h[:even] || false
      @invert = [rand(@width), rand(@height)]
      init_table_for_output
      generate_board
    end

    def to_s(aa = [@board])
      aa.map! {|ary| ary.map {|item| bin_to_str(item)}}
      if aa.size == 1
        aa.first.join("\n") + "\n"
      else
        aa1 = aa.shift
        aa1.zip(*aa).map {|item| item.join(@s[:to])}.join("\n") + "\n"
      end
    end

    def print_question
      print to_s([create_corrupt_board])
    end

    def print_question_answer
      print to_s([create_corrupt_board, create_corrupt_board(2), @board])
    end

    private

    def init_table_for_output
      if /jp/i =~ ENV["LANG"]
        @s = {
          0 => '□',
          1 => '■',
          2 => '＊',
          :to => '　→　'
        }
      else
        @s = {
          0 => '0',
          1 => '1',
          2 => '*',
          :to => ' => '
        }
      end
    end

    def generate_board
      @board = Array.new(@height - 1) do
        Array.new(@width - 1) do
          rand(2)
        end
      end

      if $DEBUG
        puts "#### step 1 ####"
        print to_s([@board])
      end

      @board.map! do |item|
        item + [(item.reduce(:+) + (@even ? 0 : 1)) % 2]
      end

      if $DEBUG
        puts "#### step 2 ####"
        print to_s([@board])
      end

      @board << @board.transpose.map do |item|
        (item.reduce(:+) + (@even ? 0 : 1)) % 2
      end

      if $DEBUG
        puts "#### step 3 ####"
        print to_s([@board])
        puts
      end

      @board
    end

    def bin_to_str(ary)
      ary.map {|c| @s[c]}.join("")
    end

    def create_corrupt_board(val = nil)
      ary = Marshal.load(Marshal.dump(@board))
      ary[@invert[1]][@invert[0]] = val || (1 - ary[@invert[1]][@invert[0]])
      ary
    end
  end

  class Manager
    def self.print_question_answer
        board = ParityProblem::Board.new
        board.print_question_answer
    end

    def self.start
      loop do
        board = ParityProblem::Board.new
        print("\033[2J\033[0;0H")
        board.print_question
        break if /^q/i =~ gets
        print("\033[2J\033[0;0H")
        board.print_question_answer
        break if /^q/i =~ gets
      end
    end
  end
end

if __FILE__ == $0
  if ARGV.empty?
    ParityProblem::Manager.start
  else
    ARGV.shift.to_i.times do
      ParityProblem::Manager.print_question_answer
      puts
    end
  end
end