advent-of-code/src/holt59/aoc/2015/day9.py

import itertools
from collections import defaultdict
from typing import Any, Iterator, cast

import parse  # type: ignore

from ..base import BaseSolver


class Solver(BaseSolver):
    def solve(self, input: str) -> Iterator[Any]:
        lines = input.splitlines()

        distances: dict[str, dict[str, int]] = defaultdict(dict)
        for line in lines:
            origin, destination, length = cast(
                tuple[str, str, int],
                parse.parse("{} to {} = {:d}", line),  # type: ignore
            )
            distances[origin][destination] = distances[destination][origin] = length

        distance_of_routes = {
            route: sum(distances[o][d] for o, d in zip(route[:-1], route[1:]))
            for route in map(tuple, itertools.permutations(distances))
        }

        yield min(distance_of_routes.values())
        yield max(distance_of_routes.values())