diff options
| -rw-r--r-- | 16.py | 66 |
1 files changed, 66 insertions, 0 deletions
@@ -0,0 +1,66 @@ +from __future__ import annotations +from utils import open_day +from bitstring import BitStream +from dataclasses import dataclass +from functools import reduce +from operator import mul, gt, lt, eq + +@dataclass +class Packet: + version: int + tag: int + contents: list[Packet] | int + +with open_day(16) as f: + bits = BitStream(bytes.fromhex(f.read().rstrip())) + +def get_packet(bits): + version, tag = bits.readlist('2*uint:3') + if tag == 4: + value = 0 + while True: + keep_going, nybble = bits.readlist('bool,uint:4') + value <<= 4 + value |= nybble + if not keep_going: break + return Packet(version, tag, value) + ltid = bits.read('uint:1') + contents = [] + if ltid == 0: + length = bits.read('uint:15') + start = bits.pos + while bits.pos - start < length: + contents.append(get_packet(bits)) + else: + packets = bits.read('uint:11') + for _ in range(packets): + contents.append(get_packet(bits)) + return Packet(version, tag, contents) + +def sum_versions(packet): + if packet.tag == 4: + return packet.version + return packet.version + sum(sum_versions(p) for p in packet.contents) + +def evaluate(packet): + def eval_all(p): + for q in p.contents: + yield evaluate(q) + def binary_op(p, op): + assert(len(p.contents) == 2) + return int(op(evaluate(p.contents[0]), evaluate(p.contents[1]))) + actions = [ + lambda p: sum(eval_all(p)), + lambda p: reduce(mul, eval_all(p), 1), + lambda p: min(eval_all(p)), + lambda p: max(eval_all(p)), + lambda p: p.contents, + lambda p: binary_op(p, gt), + lambda p: binary_op(p, lt), + lambda p: binary_op(p, eq), + ] + return actions[packet.tag](packet) + +packet = get_packet(bits) +print(sum_versions(packet)) +print(evaluate(packet)) |