aoc/2020/11/11.py

def read_file():
	with open("input.txt","r") as f:
		seed = f.read().split('\n')
		# pad with floor to prevent out-of-bounds checks
		seats = []
		seats.append(list('.' * (len(seed[0])+2)))
		for row in seed:
			seats.append(list('.' + row + '.'))
		seats.append(list('.' * (len(seed[0])+2)))
		return seats
		
def check_neighbors(state,i,j):
	a = state[i-1][j-1]
	b = state[i-1][j]
	c = state[i-1][j+1]
	d = state[i][j-1]
	e = state[i][j+1]
	f = state[i+1][j-1]
	g = state[i+1][j]
	h = state[i+1][j+1]
	return a+b+c+d+e+f+g+h

from copy import deepcopy
def find_steady_state(seats):
	height = len(seats)
	width = len(seats[0])
	state = deepcopy(seats)
	prev_state = deepcopy(seats)
	while True:
		for i in range(height):
			for j in range(width):
				cell = prev_state[i][j]
				if cell == ".":
					pass
				elif cell == "L":
					# check for no occupied seats
					neighbors = check_neighbors(prev_state,i,j)
					if "#" not in neighbors:
						state[i][j] = "#"
					else:
						state[i][j] = "L"
				elif cell == "#":
					# check for 4+ occupied seats
					neighbors = check_neighbors(prev_state,i,j)
					if neighbors.count("#") > 3:
						state[i][j] = "L"
					else:
						state[i][j] = "#"
		if state == prev_state:
			break
		prev_state = deepcopy(state)
	return state

def part1(seats):
	final_state = find_steady_state(seats)
	output = ''
	for row in final_state:
		for character in row:
			output += character
	return output.count("#")

def check_line_of_sight(state,i,j):
	height = len(state)
	width = len(state[0])
	a = "."
	n = 1
	while a == "." and i-n >= 0 and j-n >= 0:
		a = state[i-n][j-n]
		n += 1
	b = "."
	n = 1
	while b == "." and i-n >= 0:
		b = state[i-n][j]
		n += 1
	c = "."
	n = 1
	while c == "." and i-n >= 0 and j+n < width:
		c = state[i-n][j+n]
		n += 1
	d = "."
	n = 1
	while d == "." and j-n >= 0:
		d = state[i][j-n]
		n += 1
	e = "."
	n = 1
	while e == "." and j+n < width:
		e = state[i][j+n]
		n += 1
	f = "."
	n = 1
	while f == "." and i+n < height and j-n >= 0:
		f = state[i+n][j-n]
		n += 1
	g = "."
	n = 1
	while g == "." and i+n < height:
		g = state[i+n][j]
		n += 1
	h = "."
	n = 1
	while h == "." and i+n < height and j+n < width:
		h = state[i+n][j+n]
		n += 1
	return a+b+c+d+e+f+g+h

def find_steady_state_2(seats):
	height = len(seats)
	width = len(seats[0])
	state = deepcopy(seats)
	prev_state = deepcopy(seats)
	while True:
		for i in range(height):
			for j in range(width):
				cell = prev_state[i][j]
				if cell == ".":
					pass
				elif cell == "L":
					# check for no occupied seats
					neighbors = check_line_of_sight(prev_state,i,j)
					if "#" not in neighbors:
						state[i][j] = "#"
					else:
						state[i][j] = "L"
				elif cell == "#":
					# check for 4+ occupied seats
					neighbors = check_line_of_sight(prev_state,i,j)
					if neighbors.count("#") > 4:
						state[i][j] = "L"
					else:
						state[i][j] = "#"
		if state == prev_state:
			break
		prev_state = deepcopy(state)
	return state

def part2(seats):
	pass
	final_state = find_steady_state_2(seats)
	output = ''
	for row in final_state:
		for character in row:
			output += character
	return output.count("#")

def main():
	seats = read_file()
	print(part1(seats), part2(seats))

if __name__ == "__main__":
	main()