From http://www.cnblogs.com/d-e-v-i-l/p/5437027.html

SDUSTOJ/1799_cnblogs.cpp

@@ -0,0 +1,93 @@
+/* ***********************************************
+Author        :devil
+Created Time  :2016/4/26 22:47:45
+************************************************ */
+#include <cstdio>
+#include <cstring>
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <queue>
+#include <set>
+#include <map>
+#include <string>
+#include <cmath>
+#include <stdlib.h>
+using namespace std;
+#define inf 0x3f3f3f3f
+#define maxn 1010
+struct node
+{
+    int v,d;
+    node(int a=0,int b=0):v(a),d(b){}
+    bool operator < (const node &a) const
+    {
+        return d>a.d;
+    }
+};
+struct edge
+{
+    int v,cost;
+    edge(int a=0,int b=0):v(a),cost(b){}
+};
+vector<edge> eg[maxn];
+bool vis[maxn];
+int n,m,s,a,b,t,c,dis[maxn],ss[maxn],tt[maxn];
+void dijkstra(int x)
+{
+    memset(vis,false,sizeof(vis));
+    for(int i=0; i<=n; i++)
+        dis[i]=inf;
+    priority_queue<node>q;
+    while(!q.empty()) q.pop();
+    dis[x]=0;
+    q.push(node(x,0));
+    node tmp;
+    while(!q.empty())
+    {
+        tmp=q.top();
+        q.pop();
+        int u=tmp.v;
+        if(vis[u]) continue;
+        vis[u]=true;
+        for(int i=0; i<eg[u].size(); i++)
+        {
+            int v=eg[tmp.v][i].v;
+            int cost=eg[u][i].cost;
+            if(!vis[v]&&dis[v]>dis[u]+cost)
+            {
+                dis[v]=dis[u]+cost;
+                q.push(node(v,dis[v]));
+            }
+        }
+    }
+}
+int main()
+{
+    //freopen("in.txt","r",stdin);
+    while(~scanf("%d%d%d%d",&n,&m,&s,&t)&&n)
+    {
+        for(int i=1;i<=n;i++)
+            eg[i].clear();
+        while(m--)
+        {
+            scanf("%d%d%d",&a,&b,&c);
+            eg[a].push_back(edge(b,c));
+            eg[b].push_back(edge(a,c));
+        }
+        for(int i=1;i<=s;i++)
+            scanf("%d",&ss[i]);
+        for(int i=1;i<=t;i++)
+            scanf("%d",&tt[i]);
+        int ans=inf;
+        for(int i=1;i<=s;i++)
+        {
+            dijkstra(ss[i]);
+            for(int j=1;j<=t;j++)
+                ans=min(ans,dis[tt[j]]);
+        }
+        if(ans!=inf) printf("%d\n",ans);
+        else printf("What a pity!\n");
+    }
+    return 0;
+}