From 831d048ba23e2b518879be2773dd5abca74a8d3f Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Fri, 6 Dec 2019 10:30:11 +0000
Subject: Day 06

---
 day06/part2 | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100755 day06/part2

(limited to 'day06/part2')

diff --git a/day06/part2 b/day06/part2
new file mode 100755
index 0000000..f7fdfb1
--- /dev/null
+++ b/day06/part2
@@ -0,0 +1,42 @@
+#!/usr/bin/env ruby
+
+def get_depth_to(hsh, elm, to)
+  n = 0
+  loop do
+    break if elm == to
+    n += 1
+    elm = hsh[elm]
+  end
+  n
+end
+
+def get_hier(hsh, elm)
+  hier = [elm]
+  loop do
+    break if elm == "COM"
+    elm = hsh[elm]
+    hier << elm
+  end
+  hier
+end
+
+input = $stdin.readlines.map(&:strip).map{|x|x.split(")")}
+
+objects = {}
+
+input.each do |line|
+  objects[line[1]] = line[0]
+end
+
+me_hier = get_hier(objects, "YOU")
+santa_hier = get_hier(objects, "SAN")
+
+lca = nil
+me_hier.each do |obj|
+  if santa_hier.include?(obj) then
+    lca = obj
+    break
+  end
+end
+
+puts get_depth_to(objects, "YOU", lca) + get_depth_to(objects, "SAN", lca) - 2
-- 
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