aoc 2022 day13

day13_part1.py

from itertools import batched


def ordered(a, b) -> bool | None:
    match a, b:
        case int(i), int(j):
            if i == j:
                return None
            return i < j
        case list(i), list(j):
            for x, y in zip(i, j):
                if (result := ordered(x, y)) is not None:
                    return result
            if len(i) == len(j):
                return None
            return len(i) < len(j)
        case int(i), list(j):
            return ordered([i], j)
        case list(i), int(j):
            return ordered(i, [j])
        case _ as unknown:
            raise TypeError(f"Unknown type: {type(unknown)}")


with open("day13.txt") as f:
    sum_of_indexes = 0
    for i, (a, b, *_) in enumerate(batched(f, 3)):
        left, right = eval(a), eval(b)
        order = ordered(left, right)
        if order:
            sum_of_indexes += i + 1
    print(sum_of_indexes)

day13_part2.py

from functools import cmp_to_key
from itertools import batched


def ordered(a, b) -> bool | None:
    match a, b:
        case int(i), int(j):
            if i == j:
                return None
            return i < j
        case list(i), list(j):
            for x, y in zip(i, j):
                if (result := ordered(x, y)) is not None:
                    return result
            if len(i) == len(j):
                return None
            return len(i) < len(j)
        case int(i), list(j):
            return ordered([i], j)
        case list(i), int(j):
            return ordered(i, [j])
        case _ as unknown:
            raise TypeError(f"Unknown type: {type(unknown)}")


def cmp(a, b) -> int:
    if ordered(a, b):
        return -1
    else:
        return 1


divider_packets = [[[2]], [[6]]]

with open("day13.txt") as f:
    packets = []
    packets.extend(divider_packets)
    for i, (a, b, *_) in enumerate(batched(f, 3)):
        left, right = eval(a), eval(b)
        packets.append(left)
        packets.append(right)

    decoder_key = 1
    for i, packet in enumerate(sorted(packets, key=cmp_to_key(cmp))):
        if packet in divider_packets:
            decoder_key *= i + 1

    print(decoder_key)