73 lines
2.2 KiB
Python
73 lines
2.2 KiB
Python
import queue
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import numpy as np
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def load() -> np.ndarray:
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with open('../.input/day15') as f:
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lines = list(map(str.strip, f.readlines()))
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return np.array([int(num) for line in lines for num in line]).reshape((-1, len(lines)))
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def manhattan(node, goal) -> int:
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return abs(node[0] - goal[0]) + abs(node[1] - goal[1])
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def neighbors(node, shape) -> list[tuple[int, int]]:
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return list(filter(
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lambda t: 0 <= t[0] < shape[0] and 0 <= t[1] < shape[1],
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[(node[0] + 1, node[1]), (node[0] - 1, node[1]), (node[0], node[1] + 1), (node[0], node[1] - 1)]
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))
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def a_star(
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start: tuple[int, int],
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goal: tuple[int, int],
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grid: np.ndarray,
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) -> list[tuple[int, int]]:
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frontier: queue.Queue[tuple[int, tuple[int, int]]] = queue.PriorityQueue()
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parent: dict[tuple[int, int], tuple[int, int]] = {}
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cost: dict[tuple[int, int], int] = {start: 0}
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frontier.put((0, start))
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while not frontier.empty():
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current: tuple[int, int] = frontier.get()[1]
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if current == goal:
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break
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for neighbor in neighbors(current, grid.shape):
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new_cost: int = cost[current] + grid[neighbor[1]][neighbor[0]]
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if neighbor not in cost or new_cost < cost[neighbor]:
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cost[neighbor], parent[neighbor] = new_cost, current
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frontier.put((
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new_cost + manhattan(neighbor, goal),
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neighbor
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))
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path: list[tuple[int, int]] = [goal]
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while path[-1] != start:
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path.append(parent[path[-1]])
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return path[::-1]
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def solve1() -> int:
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grid = load()
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path = a_star((0, 0), (len(grid[0]) - 1, len(grid) - 1), grid)
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return sum(grid[y][x] for x, y in path[1:])
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def solve2() -> int:
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full_grid = np.tile((grid := load()), (5, 5))
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s_x, s_y = grid.shape[0], grid.shape[1]
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for i in range(5):
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for j in range(5):
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full_grid[i*s_y:i*s_y+s_y, j*s_x:j*s_x+s_x] += np.full_like(grid, i+j)
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full_grid = full_grid % 10 + (full_grid >= 10).astype(int)
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path = a_star((0, 0), (full_grid.shape[0] - 1, full_grid.shape[1] - 1), full_grid)
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return sum(full_grid[y][x] for x, y in path[1:])
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if __name__ == "__main__":
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print(solve1()) # 748
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print(solve2()) # 3045
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