1351. Count Negative Numbers in a Sorted Matrix.cpp

class Solution
{
public:
    int countNegatives(vector<vector<int>> &grid)
    {
        int n = grid.size(), m = grid[0].size();
        int i = 0, j = m - 1;
        int res = 0;
        while (i <= n - 1 && j >= 0)
        {
            if (grid[i][j] < 0)
            {
                res += n - i;
                j--;
            }
            else
            {
                i++;
            }
        }
        return res;
    }
};