Day 20 part 1 Ruby solution

Author: creideiki

20-1.rb

@@ -0,0 +1,145 @@
+#!/usr/bin/env ruby
+
+class Network
+  attr_reader :gates
+
+  def initialize(input)
+    gate_format = /^(?<name>[[:alpha:]&%]+) -> (?<outputs>.*)$/
+    @gates = {}
+
+    input.each do |line|
+      m = line.match gate_format
+      outputs = m['outputs'].split(',').map(&:strip)
+      if m['name'] == 'broadcaster'
+        name = m['name']
+        gate = Broadcaster.new(name, outputs)
+      elsif m['name'].start_with? '%'
+        name = m['name'][1..]
+        gate = Flip_Flop.new(name, outputs)
+      elsif m['name'].start_with? '&'
+        name= m['name'][1..]
+        gate = Conjunction.new(name, outputs)
+      else
+        abort "Unknown gate type #{m['name']}"
+      end
+      @gates[name] = gate
+    end
+
+    @gates.each_value do |g|
+      g.outputs.each do |o|
+        @gates[o].connect_input g.name if @gates.include? o
+      end
+    end
+
+    @button_presses = 0
+  end
+
+  def score
+    (@button_presses +
+     gates.values.map { |g| g.pulses[:low] }.reduce(&:+)) *
+      gates.values.map { |g| g.pulses[:high] }.reduce(&:+)
+  end
+
+  def step(queue)
+    source, target, signal = queue.shift
+    if @gates.include? target
+      queue + @gates[target].receive(source, signal)
+    else
+      queue
+    end
+  end
+
+  def push_button!
+    @button_presses += 1
+    queue = [['button', 'broadcaster', :low]]
+    queue = step(queue) until queue.empty?
+  end
+end
+
+class Gate
+  attr_reader :name, :inputs, :outputs, :pulses
+
+  def initialize(name, outputs)
+    @name = name
+    @outputs = outputs
+    @inputs = {}
+    @pulses = Hash.new 0
+  end
+
+  def connect_input(name)
+    @inputs[name] = nil
+  end
+
+  def receive(input, signal) end
+
+  def send(signal)
+    res = []
+    @outputs.each do |o|
+      res << [@name, o, signal]
+      @pulses[signal] += 1
+    end
+    res
+  end
+
+  def inspect
+    to_s
+  end
+
+  def to_s
+    "<#{self.class}: #{@name} -> #{@outputs.join ', '}>"
+  end
+end
+
+class Broadcaster < Gate
+  def receive(input, signal)
+    send signal
+  end
+end
+
+class Flip_Flop < Gate
+  def initialize(name, outputs)
+    super
+    @state = :off
+  end
+
+  def connect_input(name)
+    @inputs[name] = :low
+  end
+
+  def receive(input, signal)
+    return [] if signal == :high
+
+    @inputs[input] = signal
+    case @state
+    when :off
+      @state = :on
+      return send :high
+    when :on
+      @state = :off
+      return send :low
+    end
+    res
+  end
+end
+
+class Conjunction < Gate
+  def connect_input(name)
+    @inputs[name] = :low
+  end
+
+  def receive(input, signal)
+    @inputs[input] = signal
+
+    if @inputs.values.all? :high
+      return send :low
+    else
+      return send :high
+    end
+  end
+end
+
+input = File.read('20.input').lines.map(&:strip)
+
+net = Network.new(input)
+1_000.times { |_| net.push_button! }
+print net.score, "\n"