240.search-a-2d-matrix-ii.cpp

class Solution {
public:
    bool searchMatrix(vector<vector<int>>& matrix, int target) {
        int m=matrix.size(), n=matrix[0].size(); 
        int i=0, j=n-1;
        while(i<m && j>=0){
            if(matrix[i][j]==target) return true;
            if(matrix[i][j]>target)  j=j-1; 
            else  i=i+1; 
        }
        
        return false; 
    }
};