Find Valid Matrix Given Row and Column Sums

lcpy gen -n 1605   # by problem number
lcpy gen -s find_valid_matrix_given_row_and_column_sums   # by problem name

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]]

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

class Solution:
    # Time: O(rows * cols) - each cell is filled at most once by the two-pointer sweep
    # Space: O(1) extra (the output matrix is not counted)
    def restore_matrix(self, row_sum: list[int], col_sum: list[int]) -> list[list[int]]:
        rs = list(row_sum)
        cs = list(col_sum)
        rows, cols = len(rs), len(cs)
        matrix = [[0] * cols for _ in range(rows)]
        r = 0
        c = 0
        while r < rows and c < cols:
            value = min(rs[r], cs[c])
            matrix[r][c] = value
            rs[r] -= value
            cs[c] -= value
            if rs[r] == 0:
                r += 1
            if cs[c] == 0:
                c += 1
        return matrix