使用priority_queue幫忙排序，把小的挑出來，再開個vector把個數挑出來(其實可以不用heap，但我開薰><)

#define pii pair<int, int>
class Solution {
public:
    vector<int> kWeakestRows(vector<vector<int>>& mat, int k) {
        priority_queue<pii, vector<pii>, greater<pii>> pq; 
        for(int i = 0 ; i < mat.size(); i++){
            int tmp = 0;
            for(int j = 0; j < mat[i].size(); j++){
                tmp += mat[i][j];
            }
            pq.push({tmp, i});
        }
        vector<int> ans;
        for(int i = 0; i < k; i++){
            ans.push_back(pq.top().second);
            pq.pop();
        }
        return ans;
    }
};