2023: d15: ex2: add solution

This commit is contained in:
Bruno BELANYI 2023-12-15 10:59:09 +00:00
parent 90ebcbebd8
commit d15f807bd1

76
2023/d15/ex2/ex2.py Executable file
View file

@ -0,0 +1,76 @@
#!/usr/bin/env python
import dataclasses
import sys
from typing import Optional
@dataclasses.dataclass
class Lens:
label: str
num: int
def __eq__(self, other: object) -> bool:
if isinstance(other, str):
return self.label == other
return super().__eq__(other)
def solve(input: list[str]) -> int:
def compute_hash(string: str) -> int:
res = 0
for c in string:
res += ord(c)
res *= 17
res %= 256
return res
def parse_step(step: str) -> tuple[str, Optional[int]]:
if step[-1] == "-":
return step[:-1], None
label, num = step.split("=")
return label, int(num)
def find_label(label: str, box: list[Lens]) -> Optional[int]:
for i, lens in enumerate(box):
if lens.label == label:
return i
return None
def focusing_power(boxes: list[list[Lens]]) -> int:
res = 0
for box_num, box in enumerate(boxes, start=1):
for i, lens in enumerate(box, start=1):
res += box_num * i * lens.num
return res
boxes: list[list[Lens]] = [[] for _ in range(256)]
for label, num in map(parse_step, input):
box = compute_hash(label)
index = find_label(label, boxes[box])
if num is None:
# Remove label from box
if index is not None:
del boxes[box][index]
# Place len in box
elif index is not None:
boxes[box][index].num = num
else:
boxes[box].append(Lens(label, num))
return focusing_power(boxes)
def main() -> None:
input = sys.stdin.read().splitlines()
assert len(input) == 1 # Sanity check
print(solve(input[0].split(",")))
if __name__ == "__main__":
main()