题解：最短路~
#include <cstdio>
#include <utility>
#include <cstring>
#include <queue>
using namespace std;
const int N=20005;
const int INF=9999999;
typedef pair<int,int>seg;
priority_queue<seg,vector<seg>,greater<seg> >q;
int d[N],u[N],v[N],w[N],head[N],next[N],a,b,c,m,n,k,p,cnt,min;
bool vis[N];
void build(){
memset(head,-1,sizeof(head));
for(int e=1;e<=m;e++){
scanf("%d%d%d",&u[e],&v[e],&w[e]);
n=n<u[e]?u[e]:n;
n=n<v[e]?v[e]:n;
u[e+m]=v[e]; v[e+m]=u[e]; w[e+m]=w[e];
next[e]=head[u[e]]; head[u[e]]=e;
next[e+m]=head[u[e+m]]; head[u[e+m]]=e+m;
}
}
int Dijkstra(int src){
memset(vis,0,sizeof(vis));
for(int i=0;i<=n;i++)d[i]=INF;
d[src]=0;
q.push(make_pair(d[src],src));
while(!q.empty()){
seg now=q.top(); q.pop();
int x=now.second;
if (vis[x]) continue; vis[x]=1;
for(int e=head[x];e!=-1;e=next[e])
if(d[v[e]]>d[x]+w[e]){
d[v[e]]=d[x]+w[e];
q.push(make_pair(d[v[e]],v[e]));
}
}
}
int main(){
while(~scanf("%d%d%d",&m,&k,&p)){
build();
for(int e=2*m+1;e<=2*m+k;e++){
scanf("%d",&v[e]);
w[e]=0; u[e]=2*m+k+1;
next[e]=head[u[e]]; head[u[e]]=e;
}
Dijkstra(2*m+k+1);
int min=INF;
for(int i=0;i<p;i++){
scanf("%d",&a);
min=d[a]<min?d[a]:min;
}
printf("%d
",min);
}
return 0;
}