[二分搜索] leetcode 240 Search a 2D Matrix II

problem:https://leetcode.com/problems/search-a-2d-matrix-ii

         经典双指针二分查找题目。

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