adventofcode/2024/11/main.py

#!/usr/bin/env python
# -*- encoding: utf-8; py-indent-offset: 4 -*-

# Author: Sebastian Mark
# CC-BY-SA (https://creativecommons.org/licenses/by-sa/4.0/deed.de)

# pylint: disable=missing-module-docstring,missing-function-docstring,consider-using-f-string


def readinput():
    with open("input", "r", encoding="utf-8") as file:
        # initialize with a count of 1 for each number
        stones = {int(n): 1 for n in file.readline().split()}
    return stones


def blink(stone: str) -> list:
    if stone == 0:
        return [1]

    if len(str(stone)) % 2 == 0:
        # split stone
        middle = len(str(stone)) // 2
        tens = 10**middle
        first = stone // tens
        second = stone % tens
        return [first, second]

    return [stone * 2024]


def solve(stones: dict) -> dict:
    new_stones = {}

    for stone, count in stones.items():
        for num in blink(stone):
            # count of each number, remember existing occurences
            new_stones[num] = new_stones.get(num, 0) + count

    return new_stones


def main():
    # part 1 + 2
    for r in [25, 75]:
        stones = readinput()
        for _ in range(r):
            stones = solve(stones)
        print("Number of stones (%d blinks): %d" % (r, sum(stones.values())))


if __name__ == "__main__":
    main()