72 lines
2.0 KiB
Python
72 lines
2.0 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2021 Akumatic
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#
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# https://adventofcode.com/2021/day/15
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from queue import PriorityQueue
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def read_file(filename: str = "input.txt") -> tuple:
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with open(f"{__file__.rstrip('code.py')}{filename}", "r") as f:
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lines = [line for line in f.read().strip().split("\n")]
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data = list()
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for line in lines:
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data += [int(x) for x in line]
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return len(lines[0]), data
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def get_neighbor_idx(idx: int, dim: int) -> list:
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y = idx // dim
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x = idx - y * dim
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neighbors = [(x - 1, y), (x + 1, y), (x, y - 1), (x, y + 1)]
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return [n[0] + n[1]*dim for n in neighbors if 0 <= n[0] < dim and 0 <= n[1] < dim]
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def dijkstra(cavern: tuple) -> dict:
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dimension, graph = cavern[0], cavern[1]
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graph_size = len(graph)
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queue = PriorityQueue()
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queue.put((0, 0))
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dist = {0: 0}
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while not queue.empty():
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distance, idx = queue.get()
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for neighbor in get_neighbor_idx(idx, dimension):
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d = distance + graph[neighbor]
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if neighbor not in dist or dist[neighbor] > d:
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dist[neighbor] = d
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queue.put((d, neighbor))
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return dist
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def expand(cavern: tuple) -> tuple:
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dim = cavern[0]
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# expand to the right
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tmp = list()
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for y in range(dim):
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for i in range(5):
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for x in range(dim):
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idx = x + y * dim
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val = cavern[1][idx] + i
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if val > 9:
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val -= 9
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tmp.append(val)
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cave = tmp
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# expand to the bottom
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for _ in range(4):
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tmp = [n + 1 if n + 1 < 10 else n - 8 for n in tmp]
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cave += tmp
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return dim * 5, cave
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def part1(cavern: tuple) -> int:
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return dijkstra(cavern)[cavern[0]**2 - 1]
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def part2(cavern: tuple) -> int:
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cavern = expand(cavern)
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return dijkstra(cavern)[cavern[0]**2 - 1]
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if __name__ == "__main__":
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vals = read_file()
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print(f"Part 1: {part1(vals)}")
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print(f"Part 2: {part2(vals)}")
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