Distances

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define nl '\n'
#define io ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0)
const int mod = 1000000007;
const int mod2 = 998244353;

// change this
const int N = 105;

int t, n, a, b;
vector<int> arr[N], ans;

void dfs(int node, int par, int flag) {
    if (!flag) ans.push_back(node);
    for (auto i : arr[node]) {
        if (i == par) continue;
        dfs(i, node, flag^1);
    }
    if (flag) ans.push_back(node);
}

signed main() {
    io;
    cin >> t;
    while (t--) {
        ans.clear();
        cin >> n;
        for (int i=1; i<=n; i++) arr[i].clear();
        for (int i=0; i<n-1; i++) {
            cin >> a >> b;
            arr[a].push_back(b);
            arr[b].push_back(a);
        }
        dfs(1, 0, 0);
        for (auto i : ans) cout << i << ' ';
        cout << nl;
    }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED