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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))
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