P3366 模板最小生成树（Prim）

Posted 2020-12-21 ccsu-kid

https://www.luogu.com.cn/problem/P3366

 1 #define IO std::ios::sync_with_stdio(0)
 2 #include <bits/stdc++.h>
 3 #define pb push_back
 4 using namespace std;
 5 typedef long long ll;
 6 const int N=5005;
 7 const int inf=2147483647;
 8 
 9 int n,m;
10 
11 struct node{
12     int x,dis;
13 };
14 
15 vector<node>G[N];
16 
17 int vis[N],d[N];
18 
19 int Prim(){
20     fill(d+1,d+1+n,inf);
21     d[1]=0;
22     int ans=0;
23     for(int i=1;i<=n;i++){
24         int mi=inf;
25         int u=-1;
26         for(int j=1;j<=n;j++){
27             if(!vis[j]&&d[j]<mi){
28                 mi=d[j];
29                 u=j;
30             }
31         }
32         if(u==-1)return -1;
33         vis[u]=1;
34         ans+=d[u];
35         for(int j=0;j<G[u].size();j++){
36             int v=G[u][j].x;
37             if(!vis[v]&&G[u][j].dis<d[v])d[v]=G[u][j].dis;
38         }
39     }
40     return ans;
41 }
42 
43 int main(){
44     IO;
45     cin>>n>>m;
46     for(int i=1;i<=m;i++){
47         int u,v,w;
48         cin>>u>>v>>w;
49         G[u].pb((node){v,w});
50         G[v].pb((node){u,w});
51     }
52     int ans=Prim();
53     if(ans==-1)cout<<"orz"<<endl;
54     else cout<<ans<<endl;
55 }