class Solution {
public:
int countNegatives(vector<vector<int>>& grid) {
int result = 0, row = grid.size(), col = grid[0].size();
for(int i = 0, j = col - 1; i < row; i ++) {
while(j >= 0 && grid[i][j] < 0) j --;
result += col - 1 - j;
}
return result;
}
};