Доп контест 1 задача Соне

#include <iostream>
#include <vector>
using namespace std;

int parent[150000];
int my_rank[150000];
vector<int> kitty[150000];

void make_set (int v) {
    parent[v] = v;
    my_rank[v] = 0;
    kitty[v].push_back(v);
}

int find_set (int v) {
    if (v == parent[v])
        return v;
    return find_set (parent[v]);
}

void union_sets (int a, int b) {
    a = find_set (a);
    b = find_set (b);
    if (a != b) {
        if (my_rank[a] < my_rank[b])
            swap (a, b);
        parent[b] = a;
        if (my_rank[a] == my_rank[b])
            ++my_rank[a];
        int old_size = kitty[a].size();
        kitty[a].resize(kitty[a].size() + kitty[b].size());
        for (int i = 0; i < kitty[b].size(); i++){
            kitty[a][old_size + i] = kitty[b][i];
        }
        kitty[b].clear();
    }
}

void get_answer(){
    int last_cage = find_set(0);
    for (int i = 0; i < kitty[last_cage].size(); i++){
        cout << kitty[last_cage][i] + 1 << ' ';
    }
}

int main(){
    int n;
    cin >> n;
    for (int i = 0; i < n; i++)
        make_set(i);
    for (int i = 0; i < n; i++){
        int a, b;
        cin >> a >> b;
        union_sets(a - 1, b - 1);
    }
    get_answer();

}