class DuelingGenerator
  attr_reader :value, :start
  def initialize(value)
    @value = value
    @start = value
  end

  def self.for(string)
    type, value = string.gsub("Generator ", "").split(" starts with ")
    Object.const_get("DuelingGenerator::Generator#{type}").new value.to_i
  end

  def reset!
    @value = start
  end

  def generate!
    @value = (value * factor) % 2147483647
  end

  def strict_generate!
    @value = (value * factor) % 2147483647
    generate! until meets_criterion?
  end

  def meets_criterion?
    value % criterion == 0
  end

  class GeneratorA < DuelingGenerator
    def factor
      16807
    end

    def criterion
      4
    end
  end

  class GeneratorB < DuelingGenerator
    def factor
      48271
    end

    def criterion
      8
    end
  end

  class GeneratorPair
    attr_reader :g1, :g2
    def initialize(g1, g2)
      @g1 = g1
      @g2 = g2
    end

    def self.for(input)
      new *input.split("\n").map { |line| DuelingGenerator.for line }
    end

    def loose_pair_count(comparisons = 40000000)
      g1.reset!
      g2.reset!
      pairs = 0
      comparisons.times do
        g1.generate!
        g2.generate!
        pairs += 1 if g1.value & 65535 == g2.value & 65535
      end
      pairs
    end

    def strict_pair_count(comparisons = 5000000)
      g1.reset!
      g2.reset!
      pairs = 0
      comparisons.times do
        g1.strict_generate!
        g2.strict_generate!
        pairs += 1 if g1.value & 65535 == g2.value & 65535
      end
      pairs
    end
  end
end