Count negative numbers in a sorted matrix

We will iterate through each row and count the number of negative numbers in each row. We will add the count to the total count.

class Solution:
    def countNegatives(self, grid: List[List[int]]) -> int:
        ROWS, COLS = len(grid), len(grid[0])
        res = 0
        r, c = ROWS-1, 0
        while r >= 0 and c < COLS:
            if grid[r][c] < 0:
                res += COLS - c
                r -= 1
            else:
                c += 1
        return res

Time complexity: O(n)
Space complexity: O(1)