advent-of-code/2023/d09/ex1/ex1.py

32 lines
732 B
Python
Executable file

#!/usr/bin/env python
import itertools
import sys
def solve(input: list[str]) -> int:
def parse_line(line: str) -> list[int]:
return [int(n) for n in line.split()]
def parse(input: list[str]) -> list[list[int]]:
return [parse_line(line) for line in input]
def extrapolate(sequence: list[int]) -> int:
diffs = [n - p for p, n in itertools.pairwise(sequence)]
if all(n == 0 for n in diffs):
return sequence[-1]
return sequence[-1] + extrapolate(diffs)
sequences = parse(input)
return sum(extrapolate(seq) for seq in sequences)
def main() -> None:
input = sys.stdin.read().splitlines()
print(solve(input))
if __name__ == "__main__":
main()