CF F. Royal Questions kruskal

Posted 2022-05-26 guangheli

Code: 

#include<bits/stdc++.h> 
#define ll long long  
#define maxn 200004 
using namespace std;  
void setIO(string s) 
    string in=s+".in"; 
    freopen(in.c_str(),"r",stdin); 

int n,m;   
int p[maxn],tag[maxn]; 
void init() 
    for(int i=0;i<maxn;++i) p[i]=i;  
 
int find(int x) 
    return p[x]==x?x:p[x]=find(p[x]);  

struct Edge  
    int u,v,c; 
ed[maxn];         
bool cmp(Edge a,Edge b) 
    return a.c>b.c; 

int main() 
    // setIO("input");  
    init(); 
    scanf("%d%d",&n,&m);   
    for(int i=1;i<=m;++i) scanf("%d%d%d",&ed[i].u,&ed[i].v,&ed[i].c);   
    sort(ed+1,ed+1+m,cmp);  
    ll ans=0; 
    for(int i=1;i<=m;++i) 
        int a=find(ed[i].u), b=find(ed[i].v);       
        if(a!=b&&(!tag[a]||!tag[b])) ans+=1ll*ed[i].c, tag[a]|=tag[b], p[b]=a; 
        else if(a==b && !tag[a]) ans+=1ll*ed[i].c, tag[a]=1;         
       
    printf("%I64d\n",ans); 
    return 0;