advent-of-code/2020/d11/ex2/ex2.py

49 lines
1.4 KiB
Python
Executable file

#!/usr/bin/env python
import itertools
import sys
from copy import deepcopy
from typing import Iterator, List, Tuple
Grid = List[List[str]]
def update(grid: Grid) -> Grid:
def neightbours(x: int, y: int) -> Iterator[Tuple[int, int]]:
for dx, dy in itertools.product(range(-1, 2), range(-1, 2)):
if dx == 0 and dy == 0:
continue
new_x, new_y = x + dx, y + dy
while 0 <= new_x < len(grid) and 0 <= new_y < len(grid[0]):
if grid[new_x][new_y] in "L#":
yield new_x, new_y
break
new_x, new_y = new_x + dx, new_y + dy
new_grid = deepcopy(grid)
for x, y in itertools.product(range(len(grid)), range(len(grid[0]))):
num_alive = sum(grid[nx][ny] == "#" for nx, ny in neightbours(x, y))
if num_alive == 0 and grid[x][y] == "L":
new_grid[x][y] = "#"
elif num_alive >= 5 and grid[x][y] == "#":
new_grid[x][y] = "L"
return new_grid
def solve(grid: Grid) -> int:
while (new_grid := update(grid)) != grid:
grid = new_grid
return sum(sum(pos == "#" for pos in line) for line in grid)
def main() -> None:
input = [line.strip() for line in sys.stdin.readlines()]
print(solve([[line[i] for i in range(len(line))] for line in input]))
if __name__ == "__main__":
main()