C. Experiece EDU DSU learning series Codeforces

#include<bits/stdc++.h>
#define FAST ios_base::sync_with_stdio(false);cin.tie();cout.tie();
#define FILE_READ_IN freopen("input.txt","r",stdin);
#define FILE_READ_OUT freopen("output.txt","w",stdout);
using namespace std;
typedef long long ll;
typedef long double ld;
#define maxn 100
int parent[maxn]; int SIZE[maxn];
int points[maxn],extra[maxn];
int get(int u){
   if(parent[u]==u)
      return u;

   return parent[u]=get(parent[u]);
}
void make_set(int n)
{
   for(int i=1;i<=n;i++)
   {
      parent[i]=i;
      SIZE[i]=1;
      points[i]=0;
      extra[i]=0;
   }

}
void UNION(int u,int v)
{
   if(get(u)==get(v)) return;
   u=get(u);
   v=get(v);

   if(points[u]>points[v])
   {
      parent[u]=v;
      //SIZE[v]+=SIZE[u];
   }
   else
   {
      parent[v]=u;
      SIZE[u]+=SIZE[v];
      //extra[v]+=points[u];
   }
}

int main(){
    FAST
   #ifndef ONLINE_JUDGE
   FILE_READ_IN
   FILE_READ_OUT
   #endif
   int n,m; cin>>n>>m;
   make_set(n);

   for(int i=0;i<m;i++)
   {
      string cmd; cin>>cmd;
      if(cmd=="add")
      {
         int u,v; cin>>u>>v;
         int p=get(u);
         extra[u]+=points[p];
         extra[v]+=points[u];
         points[p]+=v+points[u];
      }
      else if(cmd=="join")
      {
         int u,v; cin>>u>>v;
         UNION(u,v);
      }
      else
      {
         int x; cin>>x;
         int p=get(x);
         //cout<<extra[x]<<" "<<extra[p]<<"\n";
         cout<<points[p]-extra[x]<<"\n";    // substract the points before union from the result
      }
   }

   return 0;
}