最小生成树--prim+优先队列优化模板

 1 #include<stdio.h>    //大概要这些头文件
 2 #include<string.h>
 3 #include<queue>
 4 #include<vector>
 5 #include<algorithm>
 6 using namespace std;
 7 typedef pair<int,int> pii;
 8 
 9 int head[30],next[200],point[200],val[200],size,dist[30];    //前向星及dist数组
10 bool vis[30];
11 
12 void add (int a,int b, int v){    //加边及去重
13     int i;
14     for(i=head[a];~i;i=next[i]){
15         if(point[i]==b){
16             if(val[i]>v)val[i]=v;
17             return;
18         }    
19     }
20     point[size]=b;
21     val[size]=v;
22     next[size]=head[a];
23     head[a]=size++;
24 }
25 
26 struct cmp{    //重载小根堆
27     bool operator()(pii a,pii b){
28         return a.first>b.first;
29     }
30 };
31 
32 void prim(int s){    //prim函数，传入图中一点
33     int i,ans=0;
34     memset(dist,-1,sizeof(dist));
35     memset(vis,0,sizeof(vis));
36     priority_queue<pii,vector<pii>,cmp>q;
37     for (i=head[s];~i;i=next[i]){
38         dist[point[i]]=val[i];
39         q.push(make_pair(dist[point[i]],point[i]));
40     }
41     dist[s]=0;
42     vis[s]=1;
43     while(!q.empty()){
44         pii u=q.top();
45         q.pop();
46         if(vis[u.second])continue;
47         vis[u.second]=1;
48         ans+=u.first;
49         for(i=head[u.second];~i;i=next[i]){
50             int j=point[i];
51             if(!vis[j]&&(dist[j]>val[i]||dist[j]==-1)){
52                 dist[j]=val[i];
53                 q.push(make_pair(dist[j],j));
54             }
55         }
56     }
57     printf("%d\n",ans);
58 }