61 lines
1.3 KiB
Python
61 lines
1.3 KiB
Python
import numpy as np
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from heapq import heappush, heappop
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def neighbors(pos: tuple[int, int], shape):
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n = []
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if pos[0] > 0:
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n.append((pos[0] - 1, pos[1]))
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if pos[1] > 0:
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n.append((pos[0], pos[1] - 1))
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if pos[0] != shape[0] - 1:
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n.append((pos[0] + 1, pos[1]))
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if pos[1] != shape[1] - 1:
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n.append((pos[0], pos[1] + 1))
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return n
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def dijkstra(grid):
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dist = np.full_like(grid, np.iinfo(np.int64).max)
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q = [(0, (0, 0))]
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dist[0, 0] = 0
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while q:
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_, u = heappop(q)
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for neighbour in neighbors(u, grid.shape):
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new = dist[u] + grid[neighbour]
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if new < dist[neighbour]:
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dist[neighbour] = new
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heappush(q, (new, neighbour))
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return dist[(grid.shape[0] - 1, grid.shape[1] - 1)]
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def multiply_grid(grid: np.ndarray, n=5) -> np.ndarray:
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for axis in range(2):
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to_copy = grid.copy()
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for i in range(1, n):
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new = to_copy + i
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grid = np.concatenate([grid, new], axis=axis)
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grid[grid > 9] -= 9
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return grid
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if __name__ == "__main__":
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import sys
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grid = np.array(
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[[int(x) for x in list(line.strip())] for line in sys.stdin.readlines()]
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)
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print("Part one:", dijkstra(grid))
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print("Part two:", dijkstra(multiply_grid(grid)))
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