首先只用连一次边,然后你这个 kruskal 合并集合写的不对,我给你改过来了,你可以看一下:
```cpp
#include<iostream>
#include<cstring>
#include<string>
#include<cstdio>
#include<queue>
#include<cmath>
#include<algorithm>
using namespace std;
const long long N=10000000;
long long cnt;
long long n,m;
long long ans;
long long fa[N];
long long head[N];
struct node{
long long from,to,v,next;
}edge[N];
void add(long long from,long long to,long long v){
edge[++cnt].to=to;
edge[cnt].from=from;
edge[cnt].v=v;
}
bool cmp(node a,node b){
return a.v<b.v;
}
long long find(long long x){
if(fa[x]!=x){
return fa[x]=find(fa[x]);
}else{
return x;
}
}
void with(long long x,long long y){
fa[x]=y;
}
int main(){
cin >>n>>m;
for(long long i=1;i<=n;i++)fa[i]=i;
for(long long i=1;i<=m;i++){
long long f,t,v;
cin >>f>>t>>v;
add(f,t,v);
}
long long num=0;
sort(edge+1,edge+1+m,cmp);
for(long long i=1;i<=m;i++){
long long x=edge[i].from,y=edge[i].to;
x=find(x),y=find(y);
if(x!=y){
with(x,y);
ans+=edge[i].v;
num++;
}
if(num==n-1){
cout <<ans;
return 0;
}
}
cout <<"orz";
return 0;
}
```
by Skykguj @ 2022-03-28 13:54:06
@[Skykguj](/user/524554) 他的合并对的,你错了
by StillEmpty @ 2022-03-28 14:04:48
不用建反向边
by CE_WA_TLE @ 2022-03-28 15:54:58
@[StillEmpty](/user/150956) 确实是他错了,他这个过不了。
by Skykguj @ 2022-03-28 15:59:07
@[CE_WA_TLE](/user/95612) 不是无向图吗
by ko_no_lzx_da @ 2022-03-28 16:59:20
@[ko_no_lzx_da](/user/418419) 确实不用,就是建有向边,然后连祖先??(大雾
by Aa0815 @ 2022-03-29 11:03:58
@[Aa0815](/user/397706) 懂了谢谢
by ko_no_lzx_da @ 2022-03-29 12:59:20