You have an integer matrix representing a plot of land, where the
value at that location represents the height above sea level.
A value of 0 indicates water. A pond is a region of water connected
vertically, horizontally, or diagonally.
The size of the pond is the total number of connected water cells.
Write a method to compute the sizes of all the ponds in the matrix.
Example:
Input:
0 2 1 0
0 1 0 1
1 1 0 1
0 1 0 1
Output:
1, 2, 4