Toyama.rb #05 問題2

q2.rb

module Q2
  def self.strike
    board = *(1..9)
    count = deliver(board)

    two_numbers = (board.zip(board.rotate) + board.zip(board.rotate(3))). #=> [[1, 2], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9], [9, 1], [1, 4], [2, 5], [3, 6], [4, 7], [5, 8], [6, 9], [7, 1], [8, 2], [9, 3]]
                   select {|ns| ns[0] < ns[1] }.
                   reject {|ns| ns.include?(5) }.
                   reject {|n| [[3, 4], [6, 7]].include?(n) }

    (1..4).each do |n|
      two_numbers.combination(n).each do |nums|
        next if nums.flatten.size != nums.flatten.uniq.size

        numbers = nums + board.select {|b| !nums.flatten.include?(b) }
        count += deliver(numbers)
      end
    end

    count
  end

  def self.deliver(numbers)
    return 1 if numbers.empty?

    count = 0
    numbers.each do |number|
      next_numbers = numbers.dup
      next_numbers.delete(number)
      count += deliver(next_numbers)
    end
    count
  end
end

puts "answer : #{Q2.strike}"

q2e.rb

module Q2
  def self.strike
    board = *(1..9)
    count = factorial(board.count)

    two_numbers = (board.zip(board.rotate) + board.zip(board.rotate(3))). #=> [[1, 2], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9], [9, 1], [1, 4], [2, 5], [3, 6], [4, 7], [5, 8], [6, 9], [7, 1], [8, 2], [9, 3]]
                   select {|ns| ns[0] < ns[1] }.
                   reject {|ns| ns.include?(5) }.
                   reject {|n| [[3, 4], [6, 7]].include?(n) }

    (1..4).each do |n|
      two_numbers.combination(n).each do |nums|
        next if nums.flatten.size != nums.flatten.uniq.size

        numbers = nums + board.select {|b| !nums.flatten.include?(b) }
        count += factorial(numbers.count)
      end
    end

    count
  end

  def self.factorial(number)
    (1..number).inject(1,:*)
  end
end

require 'benchmark'
Benchmark.bm do |x|
  x.report { puts "answer : #{Q2.strike}" }
end