aoc2023/day10.py

from collections import deque
from tools.aoc import AOCDay
from tools.coordinate import Coordinate
from tools.grid import Grid
from typing import Any

VALID_NEIGHBOURS = {
    Coordinate(1, 0): {
        "check": ["F", "-", "L", "S"],
        "valid": ["7", "-", "J"],
    },
    Coordinate(0, 1): {
        "check": ["7", "|", "F", "S"],
        "valid": ["J", "|", "L"],
    },
    Coordinate(-1, 0): {
        "check": ["J", "-", "7", "S"],
        "valid": ["F", "-", "L"],
    },
    Coordinate(0, -1): {
        "check": ["L", "|", "J", "S"],
        "valid": ["F", "|", "7"],
    },
}


def remove_clutter(grid: Grid, start: Coordinate):
    pipe_coords = set()
    pipe_coords.add(start)
    q = deque()
    q.append(start)
    while q:
        cur = q.pop()
        for c, v in VALID_NEIGHBOURS.items():
            dc = cur + c
            if dc not in pipe_coords and grid.get(cur) in v["check"] and grid.get(dc) in v["valid"]:
                pipe_coords.add(dc)
                q.append(dc)

    for c in grid.getActiveCells():
        if c not in pipe_coords:
            grid.set(c, False)


def get_farthest(grid: Grid, start: Coordinate) -> int:
    q = deque()
    q.append((0, start))
    visited = set()
    max_dist = 0
    while q:
        dist, cur = q.popleft()
        if cur in visited:
            continue
        visited.add(cur)
        for c, v in VALID_NEIGHBOURS.items():
            dc = cur + c
            if dc not in visited and grid.get(cur) in v["check"] and grid.get(dc) in v["valid"]:
                q.append((dist + 1, dc))
                max_dist = max(max_dist, dist + 1)

    return max_dist


def get_area(grid: Grid, start: Coordinate) -> set[Coordinate]:
    if grid.get(start):
        return set()
    area = set()
    q = deque()
    q.append(start)
    while q:
        c = q.popleft()
        if c in area:
            continue
        area.add(c)
        for n in c.getNeighbours(includeDiagonal=True):
            if grid.get(n):
                continue
            if grid.isWithinBoundaries(n):
                q.append(n)

    return area


def walk(grid: Grid) -> int:
    LOOKUP = {
        "|": {
            Coordinate(0, 1): {"o_dir": [Coordinate(-1, 0)], "i_dir": [Coordinate(1, 0)], "n_dir": Coordinate(0, 1)},
            Coordinate(0, -1): {"o_dir": [Coordinate(1, 0)], "i_dir": [Coordinate(-1, 0)], "n_dir": Coordinate(0, -1)},
        },
        "-": {
            Coordinate(1, 0): {"o_dir": [Coordinate(0, 1)], "i_dir": [Coordinate(0, -1)], "n_dir": Coordinate(1, 0)},
            Coordinate(-1, 0): {"o_dir": [Coordinate(0, -1)], "i_dir": [Coordinate(0, 1)], "n_dir": Coordinate(-1, 0)},
        },
        "7": {
            Coordinate(1, 0): {
                "o_dir": None,
                "i_dir": [Coordinate(0, -1), Coordinate(1, 0)],
                "n_dir": Coordinate(0, 1),
            },
            Coordinate(0, -1): {
                "o_dir": [Coordinate(1, 0), Coordinate(0, -1)],
                "i_dir": None,
                "n_dir": Coordinate(-1, 0),
            },
        },
        "J": {
            Coordinate(0, 1): {
                "o_dir": None,
                "i_dir": [Coordinate(1, 0), Coordinate(0, 1)],
                "n_dir": Coordinate(-1, 0),
            },
            Coordinate(1, 0): {
                "o_dir": [Coordinate(1, 0), Coordinate(0, 1)],
                "i_dir": None,
                "n_dir": Coordinate(0, -1),
            },
        },
        "F": {
            Coordinate(0, -1): {
                "o_dir": None,
                "i_dir": [Coordinate(-1, 0), Coordinate(0, -1)],
                "n_dir": Coordinate(1, 0),
            },
            Coordinate(-1, 0): {
                "o_dir": [Coordinate(-1, 0), Coordinate(0, -1)],
                "i_dir": None,
                "n_dir": Coordinate(0, 1),
            },
        },
        "L": {
            Coordinate(-1, 0): {
                "o_dir": None,
                "i_dir": [Coordinate(-1, 0), Coordinate(0, 1)],
                "n_dir": Coordinate(0, -1),
            },
            Coordinate(0, 1): {
                "o_dir": [Coordinate(-1, 0), Coordinate(0, 1)],
                "i_dir": None,
                "n_dir": Coordinate(1, 0),
            },
        },
    }

    cur = None
    for x in grid.rangeX():
        for y in grid.rangeY():
            if grid.get(Coordinate(x, y)):
                cur = Coordinate(x, y)
                break
        if cur is not None:
            break

    assert grid.get(cur) == "F"

    direction = Coordinate(0, 1)
    outside = get_area(grid, cur + Coordinate(0, -1))
    inside = set()
    visited = set()
    while cur not in visited:
        visited.add(cur)
        cur += direction
        c = grid.get(cur)
        oc = LOOKUP[c][direction]["o_dir"]
        ic = LOOKUP[c][direction]["i_dir"]

        if oc is not None:
            for doc in oc:
                check = cur + doc
                if check not in outside and not grid.get(check):
                    outside |= get_area(grid, check)

        if ic is not None:
            for dic in ic:
                check = cur + dic
                if check not in inside and not grid.get(check):
                    inside |= get_area(grid, check)

        direction = LOOKUP[c][direction]["n_dir"]

    return len(inside)


class Day(AOCDay):
    inputs = [
        [
            (4, "input10_test1"),
            (8, "input10_test2"),
            (6864, "input10"),
        ],
        [
            (4, "input10_test3"),
            (4, "input10_test4"),
            (8, "input10_test5"),
            (10, "input10_test6"),
            (349, "input10"),
        ],
    ]

    def parse_input(self) -> (Grid, Coordinate):
        grid = Grid()
        start = None
        for y, line in enumerate(self.getInput()):
            for x, ch in enumerate(line):
                if ch == ".":
                    continue
                if ch == "S":
                    start = Coordinate(x, y)
                grid.set(Coordinate(x, y), ch)

        up = grid.get(start + Coordinate(0, -1))
        down = grid.get(start + Coordinate(0, 1))
        left = grid.get(start + Coordinate(-1, 0))
        right = grid.get(start + Coordinate(1, 0))
        if up in ["7", "|", "F"]:
            if left in ["L", "-", "F"]:
                grid.set(start, "J")
            elif right in ["J", "-", "7"]:
                grid.set(start, "L")
            else:
                grid.set(start, "|")
        elif down in ["L", "|", "J"]:
            if left in ["L", "-", "F"]:
                grid.set(start, "7")
            else:
                grid.set(start, "F")
        else:
            grid.set(start, "-")

        remove_clutter(grid, start)
        return grid, start

    def part1(self) -> Any:
        grid, start = self.parse_input()
        return get_farthest(grid, start)

    def part2(self) -> Any:
        grid, _ = self.parse_input()
        return walk(grid)


if __name__ == "__main__":
    day = Day(2023, 10)
    day.run(verbose=True)