Advent of Code 2025 - Day 06 - Python

from dataclasses import dataclass
import re
from functools import reduce
from typing import Sequence
from operator import mul


@dataclass(slots=True, frozen=True)
class CephalopodMathInput:
    nums: Sequence[Sequence[int]]
    ops: Sequence[str]

    def compute(self) -> int:
        total = 0
        for i, op in enumerate(self.ops):
            nums = [row[i] for row in self.nums]
            match op:
                case "*":
                    total += reduce(mul, nums, 1)
                case "+":
                    total += sum(nums)
        return total


@dataclass(slots=True, frozen=True)
class VerticalCephalopodMathInput:
    nums: Sequence[Sequence[int]]
    ops: Sequence[str]

    def compute(self) -> int:
        total = 0
        for i, group in enumerate(self.nums):
            match self.ops[i]:
                case "*":
                    total += reduce(mul, group, 1)
                case "+":
                    total += sum(group)
        return total


def parse_data_horizontal(fp: str) -> CephalopodMathInput:
    num_pattern = r"(\d+)"
    op_pattern = r"([\*\+])"
    nums = []
    with open(fp, "r") as f:
        for line in f.readlines():
            if match := re.findall(num_pattern, line):
                nums.append(list(map(int, match)))
            elif match := re.findall(op_pattern, line):
                ops = list(match)
    return CephalopodMathInput(nums=nums, ops=ops)


def parse_data_vertical(fp: str) -> VerticalCephalopodMathInput:
    num_pattern = r"(\d+)"
    op_pattern = r"([\*\+])"
    num_as_str = []
    with open(fp, "r") as f:
        for line in f.readlines():
            if re.search(num_pattern, line):
                num_as_str.append(line)
            elif match := re.findall(op_pattern, line):
                ops = list(match)
    nums: list[list[int]] = []
    i = 0
    grouping = []
    while i < len(num_as_str[0]):
        num = ""
        for j in range(len(num_as_str)):
            num += num_as_str[j][i]
        if num.strip() == "":
            nums.append(grouping)
            grouping = []
        else:
            grouping.append(int(num.strip()))
        i += 1
    if grouping:
        nums.append(grouping)
    return VerticalCephalopodMathInput(nums=nums, ops=ops)


def part_a():
    """
    >>> fp = "day06a.txt"
    >>> v = parse_data_horizontal(fp)
    >>> total = v.compute()
    >>> assert total == 4277556
    """
    fp = "day06.txt"
    v = parse_data_horizontal(fp)
    total = v.compute()
    print(total)


def part_b():
    """
    >>> fp = "day06a.txt"
    >>> v = parse_data_vertical(fp)
    >>> total = v.compute()
    >>> assert total == 3263827
    """
    fp = "day06.txt"
    v = parse_data_vertical(fp)
    total = v.compute()
    print(total)


if __name__ == "__main__":
    part_a()
    part_b()