leetcode378

優先隊列

class Solution {
public:
    int kthSmallest(vector<vector<int>>& matrix, int k) {
        priority_queue<int>q;
        for(vector<int>v : matrix)
        {
            for(int t:v)
            {
                q.push(t);
                if(q.size()>k) q.pop();
            }
        }
        return q.top();
    }
};