【luogu 3366】【模板】最小生成树

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<algorithm>
 5 #define maxn 5003
 6 #define maxm 200005
 7 using namespace std;
 8 int read(){
 9     int x=0,f=1;char ch=getchar();
10     while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
11     while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
12     return x*f;
13 }
14 int fa[maxn],deep[maxn];
15 int n,m,tot=0,ans=0;
16 struct node{int u,v,w;}e[maxm];
17 bool cmp(node a,node b){return a.w<b.w;}
18 int find(int x){
19     if(fa[x]==x) return x;
20     else return fa[x]=find(fa[x]);
21 }
22 void unite(int x,int y){
23     x=find(x),y=find(y);
24     if(x==y) return ;
25     if(deep[x]<deep[y]) fa[x]=y;
26     else{
27         fa[y]=x;
28         if(deep[x]==deep[y]) deep[x]++;
29     }
30 }
31 bool same(int x,int y){
32     return find(x)==find(y);
33 }
34 int main(){
35     n=read(),m=read();
36     for(int i=1;i<=n;i++) fa[i]=i,deep[i]=0;
37     for(int i=1;i<=m;i++)
38         e[i].u=read(),e[i].v=read(),e[i].w=read();
39     sort(e+1,e+m+1,cmp);
40     for(int i=1;i<=m;i++){
41         if(same(e[i].u,e[i].v)) continue;
42         else{
43             unite(e[i].u,e[i].v);
44             ans+=e[i].w;
45             tot++;
46         }
47     }
48     if(tot<n-1) printf("orz");
49     else printf("%d",ans);
50     return 0;
51 }

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cstring>
 4 #include<algorithm>
 5 #define maxn 5005
 6 #define maxm 200005
 7 #define INF 0x3f3f3f3f
 8 using namespace std;
 9 int read(){
10     int x=0,f=1;char ch=getchar();
11     while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
12     while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
13     return x*f;
14 }
15 int n,m,dis[maxn],last[maxn],cnt,ans;
16 bool vis[maxn];
17 struct node{int to,next,cost;}e[2*maxm];
18 void add(int u,int v,int w){
19     e[++cnt].to=v;e[cnt].next=last[u];last[u]=cnt;e[cnt].cost=w;
20 }
21 void prim(){
22     for(int i=1;i<=n;i++) dis[i]=INF;
23     dis[1]=0;
24     for(int j=1;j<=n;j++){
25         int u=-1,minn=INF;
26         for(int i=1;i<=n;i++){
27             if(dis[i]<minn&&!vis[i]){
28                 u=i;
29                 minn=dis[i];
30             }
31         }
32         if(u==-1){
33             ans=-1;
34             return ;
35         }
36         vis[u]=1;
37         ans+=dis[u];
38         for(int i=last[u];i;i=e[i].next){
39             int v=e[i].to;
40             if(!vis[v]&&dis[v]>e[i].cost) dis[v]=e[i].cost;
41         }
42     }
43 }
44 int main(){
45     n=read(),m=read();
46     for(int i=1;i<=m;i++){
47         int u=read(),v=read(),w=read();
48         add(u,v,w);
49         add(v,u,w);
50     }
51     prim();
52     if(ans==-1) printf("orzn");
53     printf("%dn",ans);
54     return 0;
55 }