并查集模板题，学完就会了并查集_OIWiki

const int N=5e3+5;
int fa[N];

int find(int i){
    if(i!=fa[i]) fa[i]=find(fa[i]);
    return fa[i];
}
void join(int i,int j){
    int i_fa=find(i);
    int j_fa=find(j);
    fa[i_fa]=j_fa;
}

void solve(){
    for(int i=1;i<N;i++){
        fa[i]=i;
    }
    int n,m,p;cin>>n>>m>>p;
    for(int i=1;i<=m;i++){
        int x,y;cin>>x>>y;
        join(x,y);
    }

    for(int i=1;i<=p;i++){
        int x,y;cin>>x>>y;
        int fax = find(x);
        int fay = find(y);
        if(fax == fay) cout<<"Yes"<<endl;
        else cout<<"No"<<endl;
    }
}