dsu.cpp

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

template <class T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define int long long int
#define endl '\n'
#define pb push_back
#define pi pair<int, int>
#define pii pair<int, pi>
#define fir first
#define sec second
#define MAXN 2001
#define mod 1000000007

struct dsu
{
  int tot;
  vector<int> parent;
  vector<int> sz;

  dsu(int n)
  {
    parent.resize(n);
    sz.resize(n);
    tot = n;
    for (int i = 0; i < n; i++)
    {
      parent[i] = i;
      sz[i] = 1;
    }
  }
  int find_set(int i)
  {
    return parent[i] = (parent[i] == i) ? i : find_set(parent[i]);
  }
  void make_set(int x, int y)
  {
    x = find_set(x), y = find_set(y);
    if (x != y)
    {
      if (sz[x] > sz[y])
        swap(x, y);
      parent[x] = y;
      sz[y] += sz[x];
      tot--;
    }
  }
};
signed main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  dsu d(n);
  int a, b;
  cin >> a >> b;
  d.make_set(a, b);
  d.find_set(a);
}