61 lines
1.7 KiB
Python
61 lines
1.7 KiB
Python
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#!/usr/bin/env python
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import sys
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from typing import Iterator, List, Tuple
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HeightMap = List[List[int]]
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Point = Tuple[int, int]
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def solve(input: List[str]) -> int:
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height_map = [[int(c) for c in line] for line in input]
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def neighbours_of(point: Point) -> Iterator[Point]:
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for dx, dy in (-1, 0), (1, 0), (0, -1), (0, 1):
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x, y = point[0] + dx, point[1] + dy
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if x < 0 or x >= len(height_map):
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continue
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if y < 0 or y >= len(height_map[0]):
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continue
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yield x, y
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def is_low_point(point: Point) -> bool:
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for neighbour in neighbours_of(point):
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if height_map[neighbour[0]][neighbour[1]] <= height_map[point[0]][point[1]]:
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return False
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return True
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def explore_bassin(point: Point) -> int:
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to_be_seen = set(neighbours_of(point))
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explored = {point}
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bassin = {point}
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while len(to_be_seen) > 0:
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new = to_be_seen.pop()
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explored.add(new)
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if height_map[new[0]][new[1]] == 9:
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continue
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bassin.add(new)
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for neighbour in neighbours_of(new):
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if neighbour in explored:
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continue
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to_be_seen.add(neighbour)
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return len(bassin)
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points = [(x, y) for x in range(len(height_map)) for y in range(len(height_map[0]))]
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low_points = filter(is_low_point, points)
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bassin_sizes = sorted(map(explore_bassin, low_points), reverse=True)
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return bassin_sizes[0] * bassin_sizes[1] * bassin_sizes[2]
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def main() -> None:
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input = [line.strip() for line in sys.stdin.readlines()]
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print(solve(input))
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if __name__ == "__main__":
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main()
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