advent-of-code/2017/d15/ex2/ex2.py

43 lines
1.1 KiB
Python
Executable file

#!/usr/bin/env python
import functools
import itertools
import sys
from collections.abc import Iterator
def solve(input: str) -> int:
def parse(input: str) -> tuple[int, int]:
a, b = input.splitlines()
return int(a.split()[-1]), int(b.split()[-1])
def generate(seed: int, factor: int, criteria: int) -> int:
while True:
seed *= factor
seed %= 2147483647
if (seed % criteria) == 0:
return seed
def judge(a: int, b: int) -> bool:
mask = (1 << 16) - 1
return (a & mask) == (b & mask)
def iter_judgements(seed_a: int, seed_b: int) -> Iterator[bool]:
generate_a = functools.partial(generate, factor=16807, criteria=4)
generate_b = functools.partial(generate, factor=48271, criteria=8)
while True:
seed_a, seed_b = generate_a(seed_a), generate_b(seed_b)
yield judge(seed_a, seed_b)
seed_a, seed_b = parse(input)
return sum(itertools.islice(iter_judgements(seed_a, seed_b), 5000000))
def main() -> None:
input = sys.stdin.read()
print(solve(input))
if __name__ == "__main__":
main()