Make ruby/2017/15 much slower

ruby/2017/15/bin/problem

@@ -1,38 +1,7 @@
 #!/usr/bin/env ruby
+require "dueling_generator"
 
-def generate(value, factor)
-  (value * factor) % 2147483647
-end
+gg = DuelingGenerator::GeneratorPair.for STDIN.read.chomp
 
-line_1, line_2 = STDIN.read.chomp.split("\n").to_a
-generator_a_start = line_1.gsub("Generator A starts with ", "").to_i
-generator_b_start = line_2.gsub("Generator B starts with ", "").to_i
-
-a_factor = 16807
-b_factor = 48271
-
-a = generator_a_start
-b = generator_b_start
-pairs = 0
-
-40000000.times do
-  a = generate(a, a_factor)
-  b = generate(b, b_factor)
-  pairs += 1 if (a & 65535 == b & 65535)
-end
-
-puts "Part 1: #{pairs}"
-
-a = generator_a_start
-b = generator_b_start
-pairs = 0
-
-5000000.times do
-  a = generate(a, a_factor)
-  a = generate(a, a_factor) until (a % 4) == 0
-  b = generate(b, b_factor)
-  b = generate(b, b_factor) until (b % 8) == 0
-  pairs += 1 if (a & 65535 == b & 65535)
-end
-
-puts "Part 2: #{pairs}"
+puts "Part 1: #{gg.loose_pair_count}"
+puts "Part 2: #{gg.strict_pair_count}"

ruby/2017/15/lib/dueling_generator.rb

@@ -0,0 +1,85 @@
+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