this post was submitted on 03 Dec 2024
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Advent Of Code

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An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2024

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Day 3: Mull It Over

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[โ€“] [email protected] 0 points 2 weeks ago* (last edited 2 weeks ago)

Python

After a bunch of fiddling yesterday and today I finally managed to arrive at a regex-only solution for part 2. That re.DOTALL is crucial here.

import re
from pathlib import Path


def parse_input_one(input: str) -> list[tuple[int]]:
    p = re.compile(r"mul\((\d{1,3}),(\d{1,3})\)")
    return [(int(m[0]), int(m[1])) for m in p.findall(input)]


def parse_input_two(input: str) -> list[tuple[int]]:
    p = re.compile(r"don't\(\).*?do\(\)|mul\((\d{1,3}),(\d{1,3})\)", re.DOTALL)
    return [(int(m[0]), int(m[1])) for m in p.findall(input) if m[0] and m[1]]


def part_one(input: str) -> int:
    pairs = parse_input_one(input)
    return sum(map(lambda v: v[0] * v[1], pairs))


def part_two(input: str) -> int:
    pairs = parse_input_two(input)
    return sum(map(lambda v: v[0] * v[1], pairs))


if __name__ == "__main__":
    input = Path("input").read_text("utf-8")
    print(part_one(input))
    print(part_two(input))