hdu 2680 Choose the best route

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
const int inf=1024;
const int N=1024;
int n,m,vis[N],edge[N][N],dist[N];

void Dijkstra(int v0)
{
    int i,j,k,u,minx;
    for(i=1; i<=n; i++)
    {
        dist[i]=edge[v0][i];
        vis[i]=0;
    }
    vis[v0]=1;
    dist[v0]=0;
    for(i=1; i<n; i++)
    {
        minx=inf,u=v0;
        for(j=1; j<=n; j++)
        {
            if(!vis[j]&&dist[j]<minx)
            {
                minx=dist[j];
                u=j;
            }
        }
        vis[u]=1;
        for(k=1; k<=n; k++)
        {
            if(!vis[k]&&edge[u][k]<inf&&dist[u]+edge[u][k]<dist[k])
                dist[k]=dist[u]+edge[u][k];
        }
    }
}
int main()
{
    int i,j,k,u,v,w,t,ans,a,s;
    while(~scanf("%d%d%d",&n,&m,&s))
    {
        memset(edge,0,sizeof(edge));
        for(i=0; i<m; i++)
        {
            scanf("%d%d%d",&u,&v,&w);
            if(edge[v][u]==0||edge[v][u]>w)
                edge[v][u]=w;
        }

        for(i=1; i<=n; i++)
            for(j=1; j<=n; j++)
            {
                if(i==j) edge[i][j]=0;
                else if(edge[i][j]==0) edge[i][j]=inf;
            }

        scanf("%d",&w);
        ans=inf;
        Dijkstra(s);

        for(i=0; i<w; i++)
        {
            scanf("%d",&a);
            ans=min(ans,dist[a]);
        }

        if(ans<inf) printf("%d\n",ans);
        else printf("-1\n");
    }
    return 0;
}