From cdb3c720c53d85c834cac2a0c36b1834630dab5d Mon Sep 17 00:00:00 2001
From: Bill Rossi <bassguitarbill@gmail.com>
Date: Thu, 4 Dec 2025 07:01:08 -0500
Subject: [PATCH] 2017 ruby day 15

---
 ruby/2017/15/bin/problem | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 ruby/2017/15/bin/problem

diff --git a/ruby/2017/15/bin/problem b/ruby/2017/15/bin/problem
new file mode 100644
index 0000000..0cba6af
--- /dev/null
+++ b/ruby/2017/15/bin/problem
@@ -0,0 +1,38 @@
+#!/usr/bin/env ruby
+
+def generate(value, factor)
+  (value * factor) % 2147483647
+end
+
+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}"
\ No newline at end of file