B. The Social Network( ICPC Dhaka Regional 2k19)

#include<bits/stdc++.h>
using namespace std;
const int mx=1e5;
int par[mx+6],srt[mx+5],cnt;
int findP(int p){
    return par[p]==p? p: par[p]=findP(par[p]);
}
int main(){
    ios_base::sync_with_stdio(false);
    int t,n,q,u,v,tp,p,l,r,cs=1,i;
    cin>>t;
    while(t--){
        cout<<"Case "<<cs++<<":\n";
        cin>>n>>q;
        vector<int> vc[n+5];
        for (i=0; i<=n; i++) par[i]=i, srt[i]=0;
        while(q--){
            cin>>tp;
            if (!tp){
                cin>>u>>v;
                int pu=findP(u), pv=findP(v);
                if (pu==pv) continue;
                if (vc[pv].size()<vc[pu].size()) swap(pv,pu);
                for (auto it:vc[pu]) vc[pv].push_back(it);
                par[pu]=pv;
                srt[pv]=0;
            }else if (tp==1){
                cin>>u>>p;
                int pu=findP(u);
                vc[pu].push_back(p);
                srt[pu]=0;
            }else{
                cin>>u>>l>>r;
                int pu=findP(u),c=0;
                if (!srt[pu]) sort(vc[pu].begin(),vc[pu].end()), srt[pu]=1;
                int low=lower_bound(vc[pu].begin(),vc[pu].end(),l)-vc[pu].begin();
                int up =upper_bound(vc[pu].begin(),vc[pu].end(),r)-vc[pu].begin();
                cout<<up-low<<endl;
            }
        }
    }
    return 0;
}