【提高组】并查集

#include<bits/stdc++.h>
#define For(i,l,r) for(int i=l;i<=r;i++)
using namespace std;
const int M=2e5+5; 
struct node{
    int x,y,t;
}e[M];
int fa[M],n,m;
inline int cmp(const node x,const node y){return x.t<y.t;}
inline int getfa(int x){return fa[x]==x?x:getfa(fa[x]);}
inline int read(){
    int f=1,sum=0;
    char ch=getchar();
    while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
    while(isdigit(ch)){sum=(sum<<1)+(sum<<3)+(ch^48);ch=getchar();} 
    return f*sum;
}
int main(){
    n=read(),m=read();
    For(i,1,m) e[i].x=read(),e[i].y=read(),e[i].t=read();
    sort(e+1,e+m+1,cmp);
    For(i,1,n) fa[i]=i;
    For(i,1,m){ 
        int fx=getfa(e[i].x),fy=getfa(e[i].y);
        if(fx!=fy) fa[fx]=fy,n--;
        if(n==1) {printf("%d\n",e[i].t);return 0;}
    }
    printf("-1\n");
    return 0;
} 

#include<bits/stdc++.h>
#define For(i,l,r) for(int i=l;i<=r;i++)
using namespace std;
const int M=1e5+5;
int f[M],re[M];
int n,m,k,x,y,ans;
int getfa(int a){
    int fa=f[a];
    if(a!=fa){
        f[a]=getfa(fa);
        re[a]=(re[a]+re[fa])%3;   
        return f[a];
    }
    else return fa;
}
int main(){
    cin>>n>>m;
    For(i,1,n) f[i]=i;
    while(m--){
        cin>>k>>x>>y;
        if(x>n||y>n||(k==2&&x==y)){ans++;continue;}
        if(k==1){
            int fx=getfa(x),fy=getfa(y);
            if(fx==fy&&re[x]!=re[y]){ans++;continue;}    
            else if(fx!=fy){f[fx]=fy;re[fx]=(re[y]-re[x]+3)%3;}
        }
        if(k==2){
            int fx=getfa(x),fy=getfa(y);
            if(fx==fy){
                int rela=(re[x]-re[y]+3)%3;
                if(rela!=1){ans++;continue;}  
            }
            else f[fx]=fy,re[fx]=(re[y]-re[x]+4)%3;
        }
    }
    cout<<ans<<endl;
    return 0;
}