From 8c33b12b21f30724c6a6e3cc357facb7b0cc1b85 Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Fri, 25 Dec 2020 15:29:50 +0100
Subject: Add day 13

---
 13/a.rb | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 13/a.rb

(limited to '13/a.rb')

diff --git a/13/a.rb b/13/a.rb
new file mode 100644
index 0000000..ebadaf0
--- /dev/null
+++ b/13/a.rb
@@ -0,0 +1,19 @@
+earliest, notes = File.readlines('input.txt')
+earliest = earliest.to_i
+ids = notes.split(',').filter_map do |id|
+  if id != 'x'
+    id.to_i
+  end
+end
+
+best_wait = ids.max + 1
+best_id = 0
+ids.each do |id|
+  wait = id - (earliest % id)
+  if  wait < best_wait
+    best_wait = wait
+    best_id = id
+  end
+end
+
+puts best_wait * best_id
-- 
cgit v1.2.3