Since 2010

Advent of Code 2022 day 13 is done

I figured out my problem: I wasn’t correctly handing the scenario where a list had been exhausted with no result. I was incorrectly assuming that when either side of the list had been exhausted, a result must have been obtained.

Final code:

from functools import cmp_to_key
from utils import get_raw_input_as_str

def parse_raw_input(raw_input):
    return [[eval(packet) for packet in pair.splitlines()] for pair in raw_input.split("\n\n")]

def compare(left, right):
    if type(left) == type(right) == list:
        result = None
        i = 0
        while result is None:
            if len(left) != len(right) and len(left) <= i:
                return 1
            elif len(left) != len(right) and len(right) <= i:
                return -1
            elif len(left) == i and len(right) == i:
                return None
                result = compare(left[i], right[i])
                i += 1
        return result
    elif type(left) == type(right) == int:
        if left < right:
            return 1
        elif left > right:
            return -1
            return None
    elif type(left) == int and type(right) != int:
        return compare([left], right)
    elif type(right) == int and type(left) != int:
        return compare(left, [right])
        raise Exception

def part_one(input):
    return sum([i + 1 for i, pair in enumerate(input) if compare(pair[0], pair[1]) == 1])

def part_two(input):
    flattened_input = [packet for pair in input for packet in pair] + [[[2]]] + [[[6]]]
    sorted_packets = sorted(flattened_input, key=cmp_to_key(compare), reverse=True)
    return (sorted_packets.index([[2]]) + 1) * (sorted_packets.index([[6]]) + 1)

if __name__ == '__main__':
    print(f"Part one: {part_one(parse_raw_input(get_raw_input_as_str('day_13_input.txt')))}")
    print(f"Part one: {part_two(parse_raw_input(get_raw_input_as_str('day_13_input.txt')))}")