#include<tuple>
typedef std::tuple<int,int,int> ti;
class Solution_leet_code_site1 {
public:
    int findCheapestPrice(int n, std::vector<std::vector<int>>& flights, int src, int dst, int K) {
        std::vector<std::vector<std::pair<int,int>>>vp(n);
        for(const auto&f:flights)   vp[f[0]].emplace_back(f[1],f[2]);
        std::priority_queue<ti,std::vector<ti>,std::greater<ti>>pq;
        pq.emplace(0,src,K+1);
        while(!pq.empty()){
           // auto [cost,u,stops] = pq.top();//replaced for C++11 as
            int cost=std::get<0>(pq.top());
            int u=std::get<1>(pq.top());
            int stops=std::get<2>(pq.top());

            pq.pop();
            if(u==dst)  return cost;
            if(!stops)  continue;
            for(auto to:vp[u]){
                //auto [v,w] = to;//replaced for C++11 as
                int v=std::get<0>(to);
                int w=std::get<1>(to);
                pq.emplace(cost+w,v,stops-1);
            }
        }
        return -1;
    }
};