01.negative_number_in_sorted_matrix.cpp

// https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/

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