Add day 10: Balance Bots

Author: petertseng

10_balance_bots.rb

@@ -0,0 +1,47 @@
+Bot = Struct.new(:id, :nums, :low_to, :high_to) {
+  def <<(n)
+    nums << n
+    nums.sort!
+    puts id if nums == [17, 61]
+  end
+
+  def ready?
+    nums.size == 2
+  end
+
+  def run!
+    [low_to, high_to].zip(nums.shift(2)).select { |to, num|
+      to << num
+      to.is_a?(Bot) && to.ready?
+    }.map(&:first)
+  end
+}
+
+bots = Hash.new { |h, k| h[k] = Bot.new(k, []) }
+outputs = Hash.new { |h, k| h[k] = [] }
+
+ARGF.each_line { |l|
+  words = l.split
+
+  parse_target = ->(at:) {
+    case (type = words[at])
+    when 'bot'; bots
+    when 'output'; outputs
+    else raise "what is a #{type}?"
+    end[Integer(words[at + 1])]
+  }
+
+  case (cmd = words[0])
+  when 'value'; bots[Integer(words[-1])] << Integer(words[1])
+  when 'bot'
+    bot = bots[Integer(words[1])]
+    bot.low_to = parse_target[at: 5]
+    bot.high_to = parse_target[at: -2]
+  else raise "what is a #{cmd}?"
+  end
+}
+
+ready_bots = bots.values.select(&:ready?)
+ready_bots = ready_bots.flat_map(&:run!) until ready_bots.empty?
+
+puts (0..2).map { |i| outputs[i].first }.reduce(:*)