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#!/usr/bin/env python3
def neighbours(data: list[list[str]], x: int, y: int) -> int:
acc = 0
for x1, y1 in [
(x - 1, y - 1),
(x - 1, y),
(x - 1, y + 1),
(x, y - 1),
(x, y + 1),
(x + 1, y - 1),
(x + 1, y),
(x + 1, y + 1),
]:
try:
if x1 >= 0 and y1 >= 0 and data[x1][y1] == "#":
acc += 1
except IndexError:
pass
return acc
def simulate(data: list[list[str]]) -> list[list[str]]:
ndata = [["." for i in range(100)] for j in range(100)]
for i in range(100):
for j in range(100):
if (i, j) in [(0, 0), (0, 99), (99, 0), (99, 99)]:
ndata[i][j] = "#"
elif data[i][j] == "#" and neighbours(data, i, j) in [2, 3]:
ndata[i][j] = "#"
elif data[i][j] == "." and neighbours(data, i, j) == 3:
ndata[i][j] = "#"
return ndata
def main() -> None:
with open("input", "r", encoding="utf-8") as f:
data = [list(l.strip()) for l in f.readlines()]
data[0][0], data[0][99], data[99][0], data[99][99] = "#", "#", "#", "#"
for i in range(100):
data = simulate(data)
print(sum(data[i].count("#") for i in range(100)))
if __name__ == "__main__":
main()
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