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#!/usr/bin/python
import numpy as np
def init_grid(lines):
dim = len(lines[0])
grid = np.zeros((dim + 2, dim + 2), dtype="bool")
for r, line in enumerate(lines):
for c, char in enumerate(line):
if char == "#":
grid[r + 1, c + 1] = True
return grid
def solve_partn(partn, init, steps):
grid = init_grid(init)
# Part 2: some lights are stuck in the "on" state
if partn == 2:
grid[([1, 1, -2, -2], [1, -2, 1, -2])] = True
for i in range(steps):
new_grid = grid.copy()
for x in range(1, grid.shape[0] - 1):
for y in range(1, grid.shape[1] - 1):
neigh = np.sum(grid[x - 1 : x + 2, y - 1 : y + 2]) - grid[x, y]
if grid[x, y]:
if neigh < 2 or neigh > 3:
new_grid[x, y] = False
else: # not grid[x, y]
if neigh == 3:
new_grid[x, y] = True
if partn == 2:
new_grid[([1, 1, -2, -2], [1, -2, 1, -2])] = True
grid = new_grid
return np.count_nonzero(grid)
def main():
# Read initial state from input text file
with open("input.txt", "r") as f:
lines = f.read().splitlines()
print("Part 1 solution:", solve_partn(1, lines, 100)) # 821 for me
print("Part 2 solution:", solve_partn(2, lines, 100)) # 886 for me
if __name__ == "__main__":
main()
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