最短路算法--SPFA+嵌套map

hdu 2066

 

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<queue>
 #include<map>
 using namespace std;
 #define INF 0x3f3f3f3f
 const int maxn=;

 int T,S,D;
 int want[maxn];
 int nex[maxn];
 map<int ,map<int ,int > >mymap;

 bool visited[maxn];
 int dist[maxn];

 void SPFA()
 {
     memset(visited,false,sizeof(visited));
     for(int i=;i<maxn;i++)
         dist[i]=INF;

     //起初我把与0临近的城市的dist[]值也赋成了0
     //这样做是错误的
     //因为如果与0临近的城市的dist[]值为0,那么0就不会松弛与其相邻的边,直接跳出循环
     dist[]=;
     queue<int >que;
     while(!que.empty())
         que.pop();
     que.push();

     while(!que.empty())
     {
         int u=que.front();
         que.pop();
         visited[u]=false;

         for(map<int ,int >::iterator it=mymap[u].begin();it != mymap[u].end();++it)
         {
             int v=it->first;
             int weight=it->second;
             if(dist[v] > dist[u]+weight)
             {
                 dist[v]=dist[u]+weight;
                 if(!visited[v])
                 {
                     que.push(v);
                     visited[v]=true;
                 }
             }
         }
     }
 }

 int main()
 {
     while(~scanf("%d%d%d",&T,&S,&D))
     {
         mymap.clear();
         for(int i=;i<=T;i++)
         {
             int a,b,time;
             scanf("%d%d%d",&a,&b,&time);
             if(!mymap[a].count(b))
             {
                 mymap[a][b]=time;
                 mymap[b][a]=time;
             }
             else
             {
                 mymap[a][b]=(mymap[a][b] > time ? time:mymap[a][b]);
                 mymap[b][a]=(mymap[b][a] > time ? time:mymap[b][a]);
             }
         }
         for(int i=;i<=S;i++)
         {
             scanf("%d",nex+i);
             mymap[][nex[i]]=;
         }
         for(int i=;i<=D;i++)
             scanf("%d",want+i);
         SPFA();
         int ans=dist[want[]];
         for(int i=;i<=D;i++)
             ans=(dist[want[i]] < ans ? dist[want[i]]:ans);
         printf("%d\n",ans);
     }
     return ;
 }