From 6734e8dee0ff45229100bfbed9935ce080639981 Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Wed, 21 Dec 2022 15:19:10 +0000
Subject: Day 21

---
 day21/part1.rb | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 day21/part1.rb

(limited to 'day21/part1.rb')

diff --git a/day21/part1.rb b/day21/part1.rb
new file mode 100644
index 0000000..4895237
--- /dev/null
+++ b/day21/part1.rb
@@ -0,0 +1,34 @@
+monkeys = $stdin.readlines
+
+nums = {}
+
+monkeys.count.times do |mix|
+  if monkeys[mix] =~ /(\d+)/
+    val = $1.to_i
+    nums[monkeys[mix][0...4]] = $1.to_i
+    monkeys[mix] = nil
+  end
+end
+monkeys.compact!
+
+while nums["root"].nil?
+  monkeys.count.times do |mix|
+    f, a, b = monkeys[mix].scan(/[a-z]{4}/)
+    unless nums[a].nil? || nums[b].nil?
+      case monkeys[mix][11]
+      when ?+
+        nums[f] = nums[a] + nums [b]
+      when ?-
+        nums[f] = nums[a] - nums [b]
+      when ?*
+        nums[f] = nums[a] * nums [b]
+      when ?/
+        nums[f] = nums[a] / nums [b]
+      end
+      monkeys[mix] = nil
+    end
+  end
+  monkeys.compact!
+end
+
+puts nums["root"]
-- 
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