Leetcode240.搜索二维矩阵II

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