2020: d15: ex1: add solution

This commit is contained in:
Bruno BELANYI 2020-12-15 11:16:05 +01:00
parent 1c4bec86ef
commit d3da5495c9

40
2020/d15/ex1/ex1.py Executable file
View file

@ -0,0 +1,40 @@
#!/usr/bin/env python
import itertools
import sys
from collections import defaultdict
from typing import Dict, Iterator, List
def nth(iterable: Iterator[int], n: int) -> int:
return next(itertools.islice(iterable, n, None))
def spoken(spoken: List[int]) -> Iterator[int]:
turn = 0
turns: Dict[int, List[int]] = defaultdict(list)
for last in spoken:
turn += 1
turns[last].append(turn)
yield last
while True:
if len(last_turn := turns[last]) < 2:
last = 0
else:
last = last_turn[-1] - last_turn[-2]
turn += 1
turns[last].append(turn)
yield last
def solve(nums: List[int]) -> int:
return nth(spoken(nums), 2020 - 1)
def main() -> None:
input = [line.strip() for line in sys.stdin.readlines()]
assert len(input) == 1
print(solve([int(i) for i in input[0].split(",")]))
if __name__ == "__main__":
main()