advent-of-code/2023/day15.py
Mikaël Capelle ba5b01c594 2023 day 15.
2023-12-15 16:18:21 +01:00

32 lines
740 B
Python

import sys
from functools import reduce
steps = sys.stdin.read().strip().split(",")
def _hash(s: str) -> int:
return reduce(lambda v, u: ((v + ord(u)) * 17) % 256, s, 0)
# part 1
answer_1 = sum(map(_hash, steps))
print(f"answer 1 is {answer_1}")
# part 2
boxes: list[dict[str, int]] = [{} for _ in range(256)]
for step in steps:
if (i := step.find("=")) >= 0:
label, length = step[:i], int(step[i + 1 :])
boxes[_hash(label)][label] = length
else:
label = step[:-1]
boxes[_hash(label)].pop(label, None)
answer_2 = sum(
i_box * i_lens * length
for i_box, box in enumerate(boxes, start=1)
for i_lens, length in enumerate(box.values(), start=1)
)
print(f"answer 2 is {answer_2}")