[leetcode]74. Search a 2D Matrix

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

int i=0;
while(i<m && matrix[i][0]<=target)//注意i<m放在前面
{
i++;
}
i--;
for(int j=0;j<n;j++)
{
if(matrix[i][j]==target)
return true;
}
return false;
}
};