99ソルバー

99.rb

# 99というダイスゲームとは
#
# ルールとしては、まず目標値を決める。この目標値は33から99となる。
# そして、各プレイヤーはサイコロを5個振る。このサイコロの5個の出目を
# 足し算・引き算・掛け算・割り算を使って、目標値まで近づける。
# 最も目標値に近いプレイヤーが勝つ、というルールのゲーム。
#
# 詳しくは『ダイスゲーム百科』024pを参考にすること。

class Game
  attr_accessor :dices_perm, :goal, :temp_answer
  OPLIST = ["+", "-", "--", "*", "/", "//"].repeated_permutation(4)

  def initialize
    @goal = Random.rand(66) + 33
    set_dices
  end

  def set_dices
    @dices = Array.new(5) { Random.rand(6) + 1 }
    @dices_perm = @dices.permutation(5)
  end

  def goal_check(result, ops, dices, pattern)
    return if result < 0
    @temp_answer = [ops, dices, result] if @temp_answer.nil?
    if (@goal - @temp_answer[2]).abs > (@goal - result).abs
      @temp_answer = [ops, dices, result, pattern]
    end
  end

  def solve
    @dices_perm.each do |d|
      OPLIST.each do |op|
        begin
          # 7割は解ける
          goal_check(
            solve_ops(
              solve_op(d[0], d[1], op[0]),
              d[2..4].zip(op[1..3])),
            d, op, "((((a o1 b) o2 c) o3 d) o4 e)")
          break if goal == @temp_answer[2]

          # 言うてもそんなに改善はしない
          goal_check(
            solve_op(
              solve_op(
                solve_op(d[0], d[1], op[0]),
                solve_op(d[2], d[3], op[2]),
                op[1]
              ), d[4], op[3]
            ),
            d, op, "((a o1 b) o2 (c o3 b)) o4 e"
          )

        rescue ZeroDivisionError
          next
        end
      end
    end
  end

  def to_ans_s
    n = @temp_answer[0]
    o = @temp_answer[1]

    n[0], n[1] = n[1], n[0] if o[0] == "--" || o[0] == "//"
    o[0] = '-' if o[0] == "--"
    o[0] = '/' if o[0] == "//"

    case @temp_answer[3]
    when "((((a o1 b) o2 c) o3 d) o4 e)"
      a = "(#{n[0]} #{o[0]} #{n[1]})"
      n[2..4].zip(o[1..3]).each do |x|
        a = create_paren(a, x[0], x[1])
      end
    when "((a o1 b) o2 (c o3 b)) o4 e"
      a = "(#{n[0]} #{o[0]} #{n[1]})"
      n[3], n[2] = n[2], n[3] if o[2] == "--" || o[2] == "//"
      o[2] = '-' if o[2] == "--"
      o[2] = '/' if o[2] == "//"
      c = "(#{n[2]} #{o[2]} #{n[3]})"
      if o[1] == "--" || o[1] == "//"
        o[1] = '-' if o[1] == "--"
        o[1] = '/' if o[1] == "//"
        b = "(#{c} #{o[1]} #{a})"
      else
        b = "(#{a} #{o[1]} #{c})"
      end
      a = create_paren(b, n[4], o[3])
    end
    "#{a} = #{@temp_answer[2]}"
  end

  def create_paren(s, n, o)
    if o == '--' || o == '//'
      o = '-' if o == "--"
      o = '/' if o == "//"
      "(#{n} #{o} #{s})"
    else
      "(#{s} #{o} #{n})"
    end
  end

  def solve_op(a, b, o)
    case o
    when "+"
      a + b
    when "-"
      a - b
    when "--"
      b - a
    when "*"
      a * b
    when "/"
      a / b
    when "//"
      b / a
    end
  end

  def solve_ops(result, rest)
    rest.each do |r|
      result = solve_op(result, r[0], r[1])
    end
    result
  end
end

solves = 0
1000.times do
  game = Game.new
  game.solve
  print "GOAL #{game.goal}:"
  puts game.to_ans_s
  solves += 1 if game.goal == game.temp_answer[2]
end
puts solves