grid = []
to_flash = []

for line in open('data', 'r'):
    grid_line = []
    for ch in line.strip():
        grid_line.append(int(ch))
    grid.append(grid_line)

flashed = 0
step = 0
#for step in range(0, 100):
while(True):
    # Step 1: Increment
    for y in range(0, len(grid)):
        for x in range(0, len(grid[y])):
            grid[y][x] += 1
            if(grid[y][x] > 9):
                to_flash.append(tuple([y, x]))

    # Step 2: Flash
    prior_flash = flashed
    while(len(to_flash)):
        cell = to_flash[-1] # take the last one
        to_flash.pop() # remove
        flashed += 1 # count
        for y in range(-1, 2):
            new_y = cell[0] + y
            if(new_y >= 0 and new_y < len(grid)): # in bounds
                for x in range(-1, 2):
                    new_x = cell[1] + x
                    if(new_x >= 0 and new_x < len(grid[y])): # in bounds
                        grid[new_y][new_x] += 1
                        if(grid[new_y][new_x] == 10): # JUST flashed
                            to_flash.append(tuple([new_y, new_x]))

    # PART TWO ANSWER
    if(flashed - prior_flash == len(grid) * len(grid[0])):
        print('all flash step #', step + 1)
        break

    # Step 3: Reset (if flashed)
    for y in range(0, len(grid)):
        for x in range(0, len(grid[y])):
            if(grid[y][x] > 9):
                grid[y][x] = 0

    print('Step #', (step + 1), ': ', flashed)
    step += 1