leetcode 240. Search a 2D Matrix II

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties:

Integers in each row are sorted in ascending from left to right.
Integers in each column are sorted in ascending from top to bottom.
For example,

Consider the following matrix:

[
[1, 4, 7, 11, 15],
[2, 5, 8, 12, 19],
[3, 6, 9, 16, 22],
[10, 13, 14, 17, 24],
[18, 21, 23, 26, 30]
]
Given target = 5, return true.

Given target = 20, return false.

这题和之前那个search a 2d matrix 一样
解析过程如下链接

http://blog.csdn.net/fin0303/article/details/51107461

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