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A* + dijkstra(heap)

#include  < iostream >
#include  < vector >
#include  < queue >
#include  < algorithm >
using   namespace  std;

#define  MAXN 1001
#define  INF 0x7f7f7f7f

typedef pair < int , int >  PAIR;
// typedef make_pair MP;

int  dist[MAXN],n,m,S,T,K,cnt[MAXN];

vector < PAIR >  map1[MAXN],map2[MAXN];

struct  path{
     int  v,g;
    path(){};
    path( int  a, int  b):v(a),g(b){}
};


void  dijkstra(){
     int  i,u,len,v,cost;
    priority_queue < PAIR,vector < PAIR > ,greater < PAIR >   >  qu; // 最小堆
     // priority_queue<PAIR> qu; // 最大堆

    memset(dist, 0x7f , sizeof (dist));
    dist[T] = 0 ;
    qu.push(make_pair( 0 ,T));

     while ( ! qu.empty()){
        u = qu.top().second;
        len = qu.top().first;
        qu.pop();
         if (dist[u] != len) // 该路径并不是局部最短路，故不作扩展
             continue ;
         for (i = 0 ;i < map1[u].size();i ++ ){
            v = map1[u][i].second;
            cost = map1[u][i].first;
             if (dist[v] > dist[u] + cost){
                dist[v] = dist[u] + cost;
                qu.push(make_pair(dist[v],v));
            }
        }
    }
}


class  CP{
public :
     int   operator ()(path  & a,path  & b){
         return  a.g + dist[a.v]  >  b.g + dist[b.v]; // 最小堆
    }
};


int  astar(){
     int  i,v,cost,len;
    memset(cnt, 0 , sizeof (cnt));
    priority_queue < path,vector < path > ,CP >  qu;

     if (S == T)
        K ++ ;
     if (dist[S] == INF)
         return   - 1 ;
    
    qu.push(path(S, 0 ));
     while ( ! qu.empty()){
        v = qu.top().v;
        len = qu.top().g;
        qu.pop();
        cnt[v] ++ ;
         if (cnt[T] == K)
             return  len;
         if (cnt[v] > K) // 若v是S到T的K短路上的一点，则cnt[v]不可能大于K，否则已至少有从S到T的cnr[v]-1条比现计划路径短的路径，与v是S到T的K短路上的一点矛盾
             continue ;
         for (i = 0 ;i < map2[v].size();i ++ )
            qu.push(path(map2[v][i].second,len + map2[v][i].first));
    }
     return   - 1 ;
}





int  main(){
     int  i,x,y,d;
    scanf( " %d%d " , & n, & m);
     for (i = 0 ;i < m;i ++ ){
        scanf( " %d%d%d " , & x, & y, & d);
        map1[y].push_back(make_pair(d,x));
        map2[x].push_back(make_pair(d,y));
    }
    scanf( " %d%d%d " , & S, & T, & K);
    dijkstra();
    printf( " %d\n " ,astar());
     return   0 ;
}