Leetcode：378. Kth Smallest Element in a Sorted Matrix

算法：使用nth_number()函数

class Solution {public:    int kthSmallest(vector<vector<int>>& matrix, int k) {        int row=matrix.size();         int col=matrix[0].size();           int* number = new int[row*col];          for(int i=0; i<row; i++){              for(int j=0; j<col; j++){                  number[i*col+j]=matrix[i][j];              }        }          nth_element(number, number+k-1, number+(row*col));          return number[k-1];      }};

nth_number()的使用参考：
http://blog.csdn.net/guofengzai/article/details/2574225