http://acm.hdu.edu.cn/showproblem.php?pid=2680&&Choose the best route

有向图的最短路问题，坑爹啊，，用无向图代码提交后WA了n次后，又仔细看了一遍题，原来是有向图，杯具啊。。。

还有一点需要注意的是，由于要逆向思维，图要反着存，，切记，，，

AC代码：

#include<iostream>
#include<string.h>
#include<string>
#include<algorithm>
#include<queue>
#include<vector>
#define N 1010
#define MAX 999999999
using namespace std;
struct Gnode
{
    Gnode(){};
    Gnode(int num,int len):num(num),len(len){}
    int num;
    int len;
};
int dis[N];
typedef pair<int,int> pii;
int n,m,s;
void in(int &a)
{
    char ch;
    while((ch=getchar())<'0'||ch>'9');
    for(a=0;ch>='0'&&ch<='9';ch=getchar()) a=a*10+ch-'0';
}
void Dijstra(vector<vector<Gnode> >&Graph)
{
    priority_queue<pii,vector<pii>,greater<pii> >Q;
    for(int i=1;i<=n;++i) dis[i]=(i==s)?0:MAX;
    Q.push(make_pair(dis[s],s));
    while(!Q.empty())
    {
        pii cur=Q.top();
        Q.pop();
        int v=cur.second;
        if(cur.first!=dis[v]) continue;
        for(int i=0;i<Graph[v].size();++i)
        {
            int u=Graph[v][i].num;
            int len=Graph[v][i].len;
            if(dis[v]+len<dis[u])
                {
                    dis[u]=dis[v]+len;
                    Q.push(make_pair(dis[u],u));
                 }
        }
    }
}
int main()
{

    while(~scanf("%d%d%d",&n,&m,&s))
    {
        vector<vector<Gnode> >Graph(n+5);
        for(int i=0;i!=m;++i)
        {
            int a,b,c;
            in(a),in(b),in(c);
            Graph[b].push_back(Gnode(a,c));
        }
        Dijstra(Graph);
        int t;
        in(t);
        int ans=MAX;
        for(int i=0;i!=t;++i)
        {
            int a;
            in(a);
            if(ans>dis[a]) ans=dis[a];
        }
        if(ans==MAX) printf("-1\n");
        else printf("%d\n",ans);
    }return 0;
}

邻接矩阵+优先队列：

#include<queue>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
using namespace std;
#define N 1005
#define MAX 999999999
int map[N][N], LowCost[N], n, m, s;
bool flag[N];
void in(int &a)
{
    char ch;
    while((ch=getchar())<'0'||ch>'9');
    for(a=0;ch>='0'&&ch<='9';ch=getchar()) a=a*10+ch-'0';
}
struct POW{
    int i,v;
	friend bool operator<(POW a,POW b)
	{
		return a.v>b.v;
	}
};
void Dijkstra(){
    priority_queue<POW>Q;
    POW temp ;
    for(int i=1 ; i<=n ; i++){            
        flag[i] = 0;
        LowCost[i] =(i==s)?0:map[s][i];
        temp.i = i;
        temp.v =LowCost[i];
        Q.push(temp);
    } 
	int num=0;
    while(!Q.empty())
    {
        POW cur=Q.top();
          Q.pop();
         int v=cur.v;
         int k=cur.i;
		 if(flag[k]) continue;
         if(v==MAX||num==n-1)  break;
          flag[k]=1;
		  num++;
        for(int j=1; j<=n; j++ )
            if(!flag[j] && (map[k][j]+v) < LowCost[j] ){
                LowCost[j] = map[k][j] + v ;
                temp.i =j;
                temp.v = LowCost[j];
                Q.push(temp);
            }
    }
}
void Init(){
    for(int i=1 ; i<=n ; i++ )
      for(int j=1 ; j<=n ; j++ )
        map[i][j]=MAX;
}
int main(){
    int  i, x, y, weight;
    while( ~scanf("%d" , &n)){
		in(m),in(s);
        Init();
        for( i=0 ; i<m ; i++ ){
            in(x),in(y),in(weight);
            if(map[y][x]>weight) map[y][x]=weight;
        }
        Dijkstra();
        int w ,start;
          in(w);
        int Min = MAX;
        for( i=0 ; i<w ; i++){
             in(start);
            if (Min > LowCost[start])
                Min=LowCost[start];
        }
        printf("%d\n", Min==MAX?-1:Min );
    }
    return 0 ;
}