1095D - Circular Dance - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int n, a, b, cnt = 3;
    cin >> n;
    vector<int> ans;
    bool c[n + 1] = {};
    vector<int> v[n + 1];
    for (int i = 1; i <= n; i++) {
        cin >> a >> b;
        v[i].push_back(a);
        v[i].push_back(b);
    }
    ans.push_back(1);
    int tmp;
    if (v[v[1].front()].front() == v[1].back() or v[v[1].front()].back() == v[1].back()) {
        ans.push_back(v[1].front());
        ans.push_back(v[1].back());
        tmp = v[1].front();
    } 
    else {
        ans.push_back(v[1].back());
        ans.push_back(v[1].front());
        tmp = v[1].back();
    }
    c[1] = 1, c[v[1].front()] = 1, c[v[1].back()] = 1;
    while (cnt < n) {
        if (c[v[tmp].front()]) {
            ans.push_back(v[tmp].back());
            c[v[tmp].back()] = 1;
            tmp = v[tmp].front();
        }
        else {
            ans.push_back(v[tmp].front());
            c[v[tmp].front()] = 1;
            tmp = v[tmp].back();
        }
        cnt++;
    }
    for (auto x : ans) cout << x << " ";
    cout << "\n";
}