82 lines
2.5 KiB
Python
Executable file
82 lines
2.5 KiB
Python
Executable file
#!/usr/bin/env python
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import sys
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from itertools import chain
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from math import gcd
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from typing import Set, Tuple
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Position = Tuple[int, int]
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def main() -> None:
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asteroids = [[c == "#" for c in line.rstrip()] for line in sys.stdin.readlines()]
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def count_spotted(i: int, j: int) -> int:
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def is_valid(pos: Position) -> bool:
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return 0 <= pos[0] < len(asteroids) and 0 <= pos[1] < len(asteroids[0])
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def pos_around(radius: int) -> Set[Position]:
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return set(
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chain(
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filter(
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is_valid,
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(
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(i - offset, j - radius)
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for offset in range(-radius, radius + 1)
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),
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),
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filter(
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is_valid,
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(
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(i - offset, j + radius)
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for offset in range(-radius, radius + 1)
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),
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),
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filter(
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is_valid,
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(
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(i - radius, j - offset)
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for offset in range(-radius, radius + 1)
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),
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),
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filter(
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is_valid,
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(
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(i + radius, j - offset)
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for offset in range(-radius, radius + 1)
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),
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),
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)
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)
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seen: Set[Position] = set()
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ans = 0
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radius = 1
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while asteroids[i][j]: # Only do this if are on an asteroid
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to_visit = pos_around(radius)
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radius += 1
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if len(to_visit) == 0:
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break
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for pos in to_visit:
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if not asteroids[pos[0]][pos[1]]:
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continue # No asteroid there
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rel = (pos[0] - i, pos[1] - j)
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common = gcd(*rel)
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rel = (rel[0] // common, rel[1] // common)
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if rel in seen:
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continue # Already have an asteroid on this path
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seen.add(rel)
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ans += 1
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return ans
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ans, y, x = max(
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(count_spotted(i, j), i, j)
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for i in range(len(asteroids))
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for j in range(len(asteroids[0]))
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)
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print(f"({x}, {y}): {ans}")
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if __name__ == "__main__":
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main()
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