Advent of code 2023 day 20

def day20(s, *, part2=False, num_buttons=1000):
  all_ch, outputs, flipflop, inputs = {}, {}, {}, collections.defaultdict(dict)
  for line in s.splitlines():
    ch, name, rhs = re.match(r'^(.)(\w+) -> (.*)$', line).groups()
    all_ch[name], outputs[name], flipflop[name] = ch, rhs.split(', '), 0
    for output in outputs[name]:
      inputs[output][name] = 0

  counts = collections.Counter()
  period = {name: 0 for name in inputs[next(iter(inputs['rx']))]} if part2 else {}

  for button_index in range(10**9 if part2 else num_buttons):
    counts[0] += 1
    pulses = collections.deque([('button', 0, 'broadcaster'[1:])])

    while pulses:
      source, value, name = pulses.popleft()
      if name in period and value == 0:
        period[name] = button_index + 1
        if all(period.values()):
          return math.lcm(*period.values())
      match all_ch[name]:
        case '%':
          if value == 1:
            continue
          value = flipflop[name] = 1 - flipflop[name]
        case '&':
          inputs[name][source] = value
          value = 1 - all(inputs[name].values())
      for output in outputs[name]:
        counts[value] += 1
        if output not in {'rx', 'output'}:
          pulses.append((name, value, output))

  return math.prod(counts.values())