You are given two arrays `rowSum` and `colSum` of non-negative integers where `rowSum[i]` is the sum of the elements in the `ith` row and `colSum[j]` is the sum of the elements of the `jth` column of a 2D matrix. In other words, you do not know the elements of the matrix, but you do know the sums of each row and column.

Find any matrix of non-negative integers of size `rowSum.length x colSum.length` that satisfies the `rowSum` and `colSum` requirements.

Return a 2D array representing any matrix that fulfills the requirements. It's guaranteed that at least one matrix that fulfills the requirements exists.

Example 1:

    Input: rowSum = [3,8], colSum = [4,7]
    Output: [[3,0],
             [1,7]]
    Explanation:
    0th row: 3 + 0 = 3 == rowSum[0]
    1st row: 1 + 7 = 8 == rowSum[1]
    0th column: 3 + 1 = 4 == colSum[0]
    1st column: 0 + 7 = 7 == colSum[1]
    The row and column sums match, and all matrix elements are non-negative.
    Another possible matrix is: [[1,2],
                                 [3,5]]

Example 2:

    Input: rowSum = [5,7,10], colSum = [8,6,8]
    Output: [[0,5,0],
             [6,1,0],
             [2,0,8]]

Constraints:

- `1 <= rowSum.length, colSum.length <= 500`
- `0 <= rowSum[i], colSum[i] <= 108`
- `sum(rows) == sum(columns)`