Disjoint Set Union / DSU

#include <iostream>

using namespace std;

void make_set(vector <int> &parent, vector <int> &power, int v) {
    parent[v] = v;
    power[v] = 1;
    /// rank[v] = 1 /// for rank euristica
}

int leader(vector <int> &parent, int v) {
    if (parent[v] == v)
        return v;
    return parent[v] = leader(parent, parent[v]);
}

/// euristica with sets' power
void merge_set(vector <int> &parent, vector <int> &power, int a, int b) {
    a = leader(parent, a);
    b = leader(parent, b);

    if (a != b) {
        if (power[a] < power[b])
            swap(a, b);
        parent[b] = a;
        power[a] += power[b];
        /// power[b] = 0;
    }
}

/// euristica with sets' rank
void merge_set(vector <int> &parent, vector <int> &rank, int a, int b) {
    a = leader(parent, a);
    b = leader(parent, b);

    if (a != b) {
        if (rank[a] < rank[b])
            swap(a, b);
        parent[b] = a;
        if (rank[a] == rank[b])
            rank[a]++;
    }
}

int main()
{
    cout << "Hello world!" << endl;
    return 0;
}