My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Update day24.py
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2016/day24.py
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2016/day24.py
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def bfs(grid, start, goal):
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horizon = deque()
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horizon.append((start, 0))
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horizon = deque([(start, 0)])
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seen = set(start)
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while horizon:
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(x, y), dst = horizon.pop()
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if (x, y) == goal:
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return dst
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for dx, dy, in DIRS:
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for dx, dy in DIRS:
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nx, ny = x + dx, y + dy
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if (nx, ny) not in seen and valid(grid, nx, ny):
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horizon.appendleft(((nx, ny), dst + 1))
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if __name__ == '__main__':
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grid = []
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num_locs = {}
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locations = {}
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for y, line in enumerate(fileinput.input()):
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row = []
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for x, tile in enumerate(line):
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row.append(tile)
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if tile.isdigit():
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num_locs[int(tile)] = (x, y)
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locations[int(tile)] = (x, y)
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grid.append(row)
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grid.append(list(line))
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distances = {}
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max_num = max(num_locs)
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for a, b in combinations(range(max(num_locs) + 1), 2):
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dst = bfs(grid, num_locs[a], num_locs[b])
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distances[a, b] = distances[b, a] = dst
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for a, b in combinations(range(max(locations) + 1), 2):
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distances[a, b] = distances[b, a] = bfs(grid, locations[a], locations[b])
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paths = list(permutations(range(1, max_num + 1)))
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paths = list(permutations(range(1, max(locations) + 1)))
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print "Fewest steps to visit all numbers:", min(navigate(distances, path) for path in paths)
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print "Fewest steps to also return to 0:", min(navigate(distances, path, complete=True) for path in paths)