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


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),
        },
    },
}


def remove_clutter(grid: Grid, start: Coordinate):
    pipe_coords = set()
    for x in LOOKUP[grid.get(start)]:
        dir_ = LOOKUP[grid.get(start)][x]["n_dir"]
        break
    while start not in pipe_coords:
        pipe_coords.add(start)
        start += dir_
        dir_ = LOOKUP[grid.get(start)][dir_]["n_dir"]

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


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, part2: bool = False) -> int:
    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"

    pipe_len = 0
    direction = Coordinate(0, 1)
    outside = get_area(grid, cur + Coordinate(0, -1))
    inside = set()
    visited = set()
    while cur not in visited:
        pipe_len += 1
        visited.add(cur)
        cur += direction
        c = grid.get(cur)
        if part2:
            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"]

    if part2:
        return len(inside)
    else:
        return pipe_len // 2


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:
        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

    def part1(self) -> Any:
        return walk(self.parse_input())

    def part2(self) -> Any:
        return walk(self.parse_input(), True)


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