advent-of-code/src/holt59/aoc/2022/day18.py

from typing import Any, Iterator

import numpy as np

from ..base import BaseSolver


class Solver(BaseSolver):
    def solve(self, input: str) -> Iterator[Any]:
        xyz = np.asarray(
            [
                tuple(int(x) for x in row.split(","))  # type: ignore
                for row in input.splitlines()
            ]
        )

        xyz = xyz - xyz.min(axis=0) + 1

        cubes = np.zeros(xyz.max(axis=0) + 3, dtype=bool)
        cubes[xyz[:, 0], xyz[:, 1], xyz[:, 2]] = True

        faces = [(-1, 0, 0), (1, 0, 0), (0, -1, 0), (0, 1, 0), (0, 0, -1), (0, 0, 1)]

        yield sum(
            1
            for x, y, z in xyz
            for dx, dy, dz in faces
            if not cubes[x + dx, y + dy, z + dz]
        )

        visited = np.zeros_like(cubes, dtype=bool)
        queue = [(0, 0, 0)]

        n_faces = 0
        while queue:
            x, y, z = queue.pop(0)

            if visited[x, y, z]:
                continue

            visited[x, y, z] = True

            for dx, dy, dz in faces:
                nx, ny, nz = x + dx, y + dy, z + dz
                if not all(
                    n >= 0 and n < cubes.shape[i] for i, n in enumerate((nx, ny, nz))
                ):
                    continue

                if visited[nx, ny, nz]:
                    continue

                if cubes[nx, ny, nz]:
                    n_faces += 1
                else:
                    queue.append((nx, ny, nz))

        yield n_faces