advent-of-code/2023/d06/ex1/ex1.py

37 lines
995 B
Python
Executable file

#!/usr/bin/env python
import math
import sys
def solve(input: list[str]) -> int:
def parse_line(line: str) -> list[int]:
return [int(n) for n in line.split(":")[1].split()]
def solve(time: int, distance: int) -> int:
# With n being the button-held-down time.
# We want to solve: (time - n) * n > distance
# So we want the number of intergers in ]n_1, n_2[, n_1 and n_2 roots of the quadratic
# a = -1, b = time, c = -distance
determinant = time**2 - 4 * distance
if determinant <= 0:
return 0
max = time / 2
delta = math.sqrt(determinant) / 2
n_1 = max - delta
n_2 = max + delta
return math.ceil(n_2 - 1) - math.floor(n_1 + 1) + 1
times, distances = map(parse_line, input)
return math.prod(solve(t, d) for t, d in zip(times, distances))
def main() -> None:
input = sys.stdin.read().splitlines()
print(solve(input))
if __name__ == "__main__":
main()