Sorted sizes of bodies of water

water_bodies.py

#!/usr/bin/env python3
DIAGONAL_WATER = True

def dfs_from(arr, i, j):
    size = 0
    if i >= 0 and j >= 0 and i < len(arr) and j < len(arr) and arr[i][j] == 0:
        arr[i][j] = -1  # Mark visited
        size += 1
        size += dfs_from(arr, i, j + 1) # right
        size += dfs_from(arr, i + 1, j) # down
        size += dfs_from(arr, i, j - 1) # left
        size += dfs_from(arr, i - 1, j) # up

        # Diagonals?
        if DIAGONAL_WATER:
            size += dfs_from(arr, i - 1, j + 1) # NE
            size += dfs_from(arr, i + 1, j + 1) # SE
            size += dfs_from(arr, i + 1, j - 1) # SW
            size += dfs_from(arr, i - 1, j - 1) # NW

    return size

def water_bodies(arr, n):
    bodies = []
    for i in range(n):
        for j in range(n):
          if arr[i][j] == 0:
              bodies.append(dfs_from(arr, i, j))

    return bodies

def main():
    n = int(input())
    lines = []
    for i in range(n):
        lines.append(list(map(int, input().split())))

    for body_size in sorted(water_bodies(lines, n)):
        print(body_size)

if __name__ == '__main__':
    main()

INPUT:

4
0 2 1 0
0 1 0 1
1 1 0 1
0 1 0 1

OUTPUT:

1
2
4