77 lines
1.8 KiB
Python
Executable file
77 lines
1.8 KiB
Python
Executable file
#!/usr/bin/env python
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import dataclasses
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import sys
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from typing import Optional
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@dataclasses.dataclass
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class Lens:
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label: str
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num: int
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def __eq__(self, other: object) -> bool:
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if isinstance(other, str):
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return self.label == other
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return super().__eq__(other)
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def solve(input: list[str]) -> int:
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def compute_hash(string: str) -> int:
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res = 0
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for c in string:
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res += ord(c)
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res *= 17
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res %= 256
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return res
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def parse_step(step: str) -> tuple[str, Optional[int]]:
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if step[-1] == "-":
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return step[:-1], None
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label, num = step.split("=")
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return label, int(num)
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def find_label(label: str, box: list[Lens]) -> Optional[int]:
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for i, lens in enumerate(box):
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if lens.label == label:
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return i
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return None
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def focusing_power(boxes: list[list[Lens]]) -> int:
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res = 0
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for box_num, box in enumerate(boxes, start=1):
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for i, lens in enumerate(box, start=1):
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res += box_num * i * lens.num
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return res
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boxes: list[list[Lens]] = [[] for _ in range(256)]
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for label, num in map(parse_step, input):
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box = compute_hash(label)
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index = find_label(label, boxes[box])
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if num is None:
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# Remove label from box
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if index is not None:
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del boxes[box][index]
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# Place len in box
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elif index is not None:
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boxes[box][index].num = num
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else:
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boxes[box].append(Lens(label, num))
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return focusing_power(boxes)
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def main() -> None:
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input = sys.stdin.read().splitlines()
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assert len(input) == 1 # Sanity check
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print(solve(input[0].split(",")))
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if __name__ == "__main__":
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main()
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