POJ 1511 Invitation Cards

解题思路:Dijsktra+堆优化

  1 #include<cstdio>
  2 #include<queue>
  3 #include<algorithm>
  4 #include<cstring>
  5 #define MAX 1100000
  6 using namespace std;
  7 int head[MAX],top;
  8 int dis[MAX],vis[MAX];
  9 struct edge{
 10     int from;
 11     int to;
 12     int cost;
 13     int next;
 14 }e[MAX],save[MAX];
 15 void push_front(int from,int to,int cost)
 16 {
 17     top++;
 18     e[top].from=from;
 19     e[top].to=to;
 20     e[top].cost=cost;
 21     e[top].next=head[from];
 22     head[from]=top;
 23 }
 24 struct Node{
 25     int x;
 26     int cost;
 27     bool operator<(const Node &b)const
 28     {
 29 
 30         return b.cost<cost;
 31     }
 32 }temp,p,sta;
 33 void bfs(int s)
 34 {
 35     sta.x=s;
 36     sta.cost=0;
 37     memset(vis,0,sizeof(vis));
 38     memset(dis,0,sizeof(dis));
 39     priority_queue<Node> que;
 40     que.push(sta);
 41     while(!que.empty())
 42     {
 43         p=que.top();
 44         que.pop();
 45         if(!vis[p.x])
 46         {
 47             vis[p.x]=1;
 48             dis[p.x]=p.cost;
 49             for(int i=head[p.x];i!=0;i=e[i].next)
 50             {
 51                 temp.x=e[i].to;
 52                 if(!vis[temp.x])
 53                 {
 54                     temp.cost=p.cost+e[i].cost;
 55                     que.push(temp);
 56 
 57                 }
 58             }
 59         }
 60     }
 61    // printf("%d\n",dis[en]);
 62 }
 63 int main()
 64 {
 65     int t,q,n;
 66     while(~scanf("%d",&t))
 67     {
 68         while(t--)
 69         {
 70 
 71             scanf("%d%d",&n,&q);
 72             for(int i=1; i<=q; i++)
 73             {
 74                 int u,v,c;
 75                 scanf("%d%d%d",&u,&v,&c);
 76                 save[i].from=u,save[i].to=v,save[i].cost=c;
 77             }
 78             long long ans=0;
 79             ///1
 80             top=0;
 81             memset(head,0,sizeof(head));
 82             for(int i=1;i<=q;i++)
 83                 push_front(save[i].from,save[i].to,save[i].cost);
 84             bfs(1);
 85             for(int i=1;i<=n;i++)ans+=dis[i];
 86             ///2
 87             top=0;
 88             memset(head,0,sizeof(head));
 89             for(int i=1;i<=q;i++)
 90                 push_front(save[i].to,save[i].from,save[i].cost);
 91             bfs(1);
 92             for(int i=1;i<=n;i++)ans+=dis[i];
 93 
 94             ///
 95             printf("%lld\n",ans);
 96 
 97 
 98         }
 99 
100     }
101     return 0;
102 }

 

posted @ 2018-07-01 23:28  duck_lu  阅读(162)  评论(0)  编辑  收藏  举报