aoc-2020/11.py

lines = []

with open("11.input") as f:
    for line in f.readlines():
        lines.append(list(line.strip()))

def pretty_print(map):
    print('=' * 20)
    for line in map:
        for c in line:
            print(c, end='')
        print("")

def occupied_count(map, x_in, y_in, distance):
    dirs = [
            (-1, -1), (-1, 0), (-1, 1),
            (0, -1),          (0, 1),
            (1, -1), (1, 0), (1, 1),
            ]
    count = 0
    for (y_dir, x_dir) in dirs:
        for i in range(1, distance + 1):
            y = y_in + y_dir * i
            x = x_in + x_dir * i
            if y < 0:
                break
            if x < 0:
                break
            if y > len(map) - 1:
                break
            if x > len(map[0]) - 1:
                break
            char = map[y][x]
            if char == '.':
                continue
            elif char == 'L':
                break
            elif char == '#':
                count += 1
                break
    return count

def transform(map, distance, tolerance):
    next = list(map)
    for (y, line) in enumerate(map):
        next[y] = list(line)
        for (x, char) in enumerate(line):
            if char == '.':
                continue
            elif char == 'L':
                if occupied_count(map, x, y, distance) == 0:
                    next[y][x] = '#'
            elif char == '#':
                if occupied_count(map, x, y, distance) >= tolerance:
                    next[y][x] = 'L'
    return next


def iterate(map, distance, tolerance):
    current = map
    while True:
        next = transform(current, distance, tolerance)
        #pretty_print(next)
        if next == current:
            break
        current = next
    return current

print(len([c for l in iterate(lines, 1, 4) for c in l if c == '#']))
print(len([c for l in iterate(lines, 1000, 5) for c in l if c == '#']))

current = lines