7.旅行二

就是dijkstra，只是他有很多个起点，那么我们只要用一个超级源点，让他到每一个七点的距离为0

#include<iostream>
#include<stdio.h>
#include<cmath>
#include<float.h>
#include<string.h>
#include<algorithm>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#define sf scanf
#define pf printf
#define scf(x) scanf("%lld",&x)
#define scff(x,y) scanf("%d%d",&x,&y)
#define scfff(x,y,z) scanf("%lld%lld%lld",&x,&y,&z)
#define prf(x) printf("%lld\n",x)
#define mm(x,b) memset((x),(b),sizeof(x))
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=a;i>=n;i--)
#define de(x) cout<<#x<<"="<<x<<","
#define all(x) x.begin(),x.end()
#define dee(x) cout<<#x<<"="<<x<<"\n"
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
typedef long long ll;
const ll mod=1e9+7;
const double eps=1e-8;
const ll inf=0x3f3f3f3f;
using namespace std;
const double pi=acos(-1.0);
const int N=1e5+10;
struct Node
{
	ll v,dis;
	Node(ll a=0,ll b=0)
	{
		v=a;dis=b;
	}
	friend bool operator <(Node a,Node b)
	{
		return a.dis >b.dis;
	}
};
priority_queue<Node> v;
struct Edge
{
	ll to,next,w;
}edge[N*7];
ll cnt,node[N],dis[N];
bool visit[N];
void add_edge(ll x,ll y,ll w)
{
	edge[cnt].to =y;
	edge[cnt].next =node[x];
	edge[cnt].w =w;
	node[x]=cnt++;
}
void dijkstra(int x)
{
	mm(dis,inf);
	mm(visit,false);
	dis[x]=0;
	Node t;
	v.push(Node(x,0)); 
	while(!v.empty())
	{
		t=v.top();
		v.pop();
		ll u=t.v;
		if(visit[u]) continue;
		visit[u]=1;
		for(int i=node[u];i!=-1;i=edge[i].next)
		{
			ll to=edge[i].to,w=edge[i].w;
			if(!visit[to]&&dis[to]>dis[u]+w)
			{
				dis[to]=dis[u]+w;
				v.push(Node(to,dis[to]));
			}
		}
	}
}
int main()
{
	ll n,m,t,p;ll x,y,w;
	cnt=0;mm(node,-1);
	cin>>n>>m>>t>>p;
	while(m--)
	{
		scfff(x,y,w);
		add_edge(x,y,w);
		add_edge(y,x,w);
	}
	while(t--)
	{
		scf(x);
		add_edge(0,x,0);
	}
	map<ll,int> v;
	while(p--)
	{
		scf(x);
		v.insert(make_pair(x,1));
	}
	map<ll,int>::iterator it;
	dijkstra(0);
	ll ans=inf*100;
	rep(i,1,n+1)
	{
		it=v.find(i);
		if(it!=v.end())
		ans=min(ans,dis[i]); 
	}
	cout<<ans;
	return 0;
}