dsu_shortest_code.cpp

struct UnionFind {
  vector<int> p;

  UnionFind(int n) : p(vector<int>(n, 0)) {
    for (int i = 0; i < n; i++)
      p[i] = i;
  }

  int findset(int x) { return x == p[x] ? x : p[x] = findset(p[x]); }

  void merge(int x, int y) { p[findset(x)] = findset(y); }
};