78 lines
2.1 KiB
Python
Executable file
78 lines
2.1 KiB
Python
Executable file
#!/usr/bin/env python
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import re
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import sys
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from copy import deepcopy
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from dataclasses import dataclass
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from math import gcd
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from typing import List
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@dataclass
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class Position:
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x: int
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y: int
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z: int
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def line_to_pos(l: str) -> Position:
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"<x=4, y=1, z=1>"
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regex = r"<x=(?P<x>[^,]*), y=(?P<y>[^,]*), z=(?P<z>[^,]*)>"
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match = re.search(regex, l)
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assert match is not None # Sanity check
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return Position(*(int(match.group(g)) for g in ("x", "y", "z")))
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def lcm(a: int, b: int, c: int) -> int:
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def lcm_2(a: int, b: int) -> int:
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return abs(a * b) // gcd(a, b)
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return lcm_2(lcm_2(a, b), c)
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def main() -> None:
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asteroids = [line_to_pos(line) for line in sys.stdin.readlines()]
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velocities = [Position(0, 0, 0) for __ in asteroids]
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cycles: List[int] = []
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for attr in ("x", "y", "z"):
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all_prev_pos = [deepcopy(asteroids)]
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all_prev_vel = [deepcopy(velocities)]
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i = 0
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found = False
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while not found:
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i += 1
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for orig, v in zip(asteroids, velocities):
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for other in asteroids:
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if orig.x != other.x:
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v.x += 1 if orig.x < other.x else -1
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if orig.y != other.y:
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v.y += 1 if orig.y < other.y else -1
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if orig.z != other.z:
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v.z += 1 if orig.z < other.z else -1
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for asteroid, v in zip(asteroids, velocities):
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asteroid.x += v.x
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asteroid.y += v.y
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asteroid.z += v.z
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for old_pos, old_vel in zip(all_prev_pos, all_prev_vel):
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if all(
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n.__getattribute__(attr) == o.__getattribute__(attr)
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for n, o in zip(asteroids, old_pos)
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) and all(
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n.__getattribute__(attr) == o.__getattribute__(attr)
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for n, o in zip(velocities, old_vel)
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):
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found = True
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cycles.append(i)
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print(lcm(*cycles))
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if __name__ == "__main__":
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main()
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