378. 有序矩阵中第K小的元素

 1 class Solution 
 2 {
 3 public:
 4     int kthSmallest(vector<vector<int>>& matrix, int k) 
 5     {
 6         priority_queue<int,vector<int>,greater<int>> pq;
 7         int n = matrix.size();
 8         for(int i = 0;i < n;i ++)
 9         {
10             for(int j = 0;j < n;j ++) pq.push(matrix[i][j]);
11         }
12         while(--k && !pq.empty()) pq.pop();
13         return pq.top();
14     }
15 };