1 files changed, 34 insertions, 0 deletions
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"]