??? ???? 6??? ????? ?? ??? ???? ?? 2D ???? 10?? ??? ????. ? ??? ?? ?? ??(DFS)? ?? ???? ?????.

AI? ?? ?? ????

??? ???? ?????. ?? (x, y) ???? ?? ??? ???? ? ?? ??(0-9)??, 9? ???? ?????. ?? ?? ??? ?? ??? ??? ????? ?????.

def parse(input: str) -> dict[tuple[int, int], int | None]:
    return {
        (x, y): int(item) if item.isdigit() else None
        for y, row in enumerate(input.strip().splitlines())
        for x, item in enumerate(row)
    }

???? ??? ???(?? 0)?? ??(?? 9)?? ???? ??? ??? ??? 1? ?????. next_step ??? ??? ?? ??? ?????.

TRAIL_MAX = 9

def next_step(
    topo_map: dict[tuple[int, int], int | None], x: int, y: int
) -> tuple[tuple[int, int], ...]:
    assert topo_map[(x, y)] != TRAIL_MAX

    return tuple(
        incoming
        for incoming in (
            (x + 1, y),
            (x, y + 1),
            (x - 1, y),
            (x, y - 1),
        )
        if (
            isinstance(topo_map.get(incoming), int)
            and isinstance(topo_map.get((x, y)), int)
            and (topo_map[incoming] - topo_map[(x, y)] == 1)
        )
    )

?????(?? 0)? find_trailheads:

TRAILHEAD = 0

def find_trailheads(
    topo_map: dict[tuple[int, int], int | None],
) -> tuple[tuple[int, int], ...]:
    return tuple(key for key, value in topo_map.items() if value == TRAILHEAD)

???? ??? ??????? ??? climb ?????. Wikipedia? DFS ??? ?? ????? ?? ? ??? ??? ?????.

??????? ??? ??

?? ??? "??"?? ? ?? ? ??? ?????. climb ??? DFS ????? ?????.

def climb(
    topo_map: dict[tuple[int, int], int | None], trailheads: tuple[tuple[int, int], ...]
) -> dict[
    tuple[tuple[int, int], tuple[int, int]], tuple[tuple[tuple[int, int], ...], ...]
]:
    candidates: list[tuple[tuple[int, int], ...]] = [(head,) for head in trailheads]

    result = {}

    while candidates:
        current = candidates.pop()
        while True:
            if topo_map[current[-1]] == TRAIL_MAX:
                result[(current[0], current[-1])] = result.get(
                    (current[0], current[-1]), ()
                ) + (current,)
                break

            elif steps := next_step(topo_map, *current[-1]):
                incoming, *rest = steps

                candidates.extend([current + (step,) for step in rest])

                current = current + (incoming,)
            else:
                break

    return result

else ?? break? ??? ??? ???? ?? ??? ?????. ? ??? ? ??? ???? ????? ?? ??? ?????.

1???? ??? ?? ???? ?????.

def part1(input: str) -> int:
    topo_map = parse(input)

    return len(climb(topo_map, find_trailheads(topo_map)))

2???? ?? ?? ??? ?????.

def part2(input: str) -> int:
    topo_map = parse(input)

    return sum(
        len(routes) for routes in climb(topo_map, find_trailheads(topo_map)).values()
    )

?? ?? ??(?: ??? ?? ?? ??? ?? ??? ??)? ????? ? ???? ??? ?????. ?? ?? ??? ??? ?? ? ??? ???? ?????. ?? ??? ?????. ?? Python ???? ?? ??? ?????. ?????!

? ??? ?? ?? ??? ??? ???, Advent of Code day 10? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!