gistfile1.rb

#!/usr/bin/ruby -wKU
# -*- coding: utf-8 -*-
require 'pp'
module Tictactoe
  class Game
    def initialize player1, player2, size=3
      @board = Board.new(size)
      @players = [player1, player2,]
      @players.map{ |p| p.board = @board }
      @turn = 0
    end
    def start
      while @board.finish?
        color = step
        return color if color != :next
      end
      :draw
    end
    private
    def step
      player = @players[@turn]
      if @board.check(*player.think)
        return player.color
      end
      @turn ^= 1
      :next
    end
  end
  class Board
    attr_reader :size
    def initialize size=3
      @size = size
      @board = Array.new(@size**2){ |e| nil }
      @pattern = pattern
    end
    def checked? x, y
      @board[x + y * @size] != nil
    end
    def check x, y, color
      @board[x + y * @size] = color
      won? color
    end
    def finish?
      not @board.grep(nil).empty?
    end
    def empty
      @board.grep(nil)
    end
    private
    def won? color
      @pattern.each do |ptn|
        return color if @board.values_at(*ptn).all?{ |e| e == color }
      end
      false
    end
    def pattern
      board = (0...@size**2).to_a
      pattern = []
      # 横方向
      0.step(board.size - 1, @size){ |i| pattern << board[i, @size] }
      # 縦方向
      (0...@size).each{ |i| pattern << board.select{ |e| e if e % @size == i } }
      # 斜め方向
      tmp = []
      (0...@size).inject(0){ |r,v| tmp << r; r+= @size + 1; }
      pattern << tmp
      tmp = []
      (0...@size).inject(0){ |r,v| tmp << r += @size - 1; r }
      pattern << tmp
    end
  end
  class Player
    attr_accessor :board
    attr_reader   :color
    def initialize color
      @color = color
    end
    def think
      loop do
        x, y = rand(@board.size), rand(@board.size)
        unless @board.checked?(x, y)
          return [x, y, @color]
        end
      end
    end
  end
end

total = {}
(0...10000).step do
  game = Tictactoe::Game.new(Tictactoe::Player.new(:red), Tictactoe::Player.new(:blue))
  result = game.start
  total[result]||= 0
  total[result] += 1
end
p total