Distances

#include <bits/stdc++.h>
#define X first
#define Y second
#define sz(a) (int)a.size()
#define pb push_back
#define int long long

using namespace std;
typedef long long ll;

void solve();

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int t = 1;
    cin >> t;
    while (t--)
        solve();
    return 0;
}

vector <int> g[110];

bitset <110> b, uncolor;

vector <int> pans;

void dfs2(int v, int d, int pr = -1) {
    if (d == 2 && !b[v]) {
        uncolor[v] = 1;
        return;
    }
    for (auto u : g[v]) {
        if (u != pr && !b[u] && !uncolor[u])
            dfs2(u, d + 1, v);
    }
}

void dfs(int v) {
    if (!uncolor[v])
        pans.pb(v + 1);
    b[v] = 1;
    dfs2(v, 0);
    for (auto i : g[v]) {
        if (!b[i]) {
            dfs(i);
        }
    }
    if (uncolor[v])
        pans.pb(v + 1);
}

/*/
1 2
1 3
2 10
2 11
3 4
3 5
4 6
4 7
5 8
5 9
6 12
12 13
/*/
void solve() {
    b = 0;
    uncolor = 0;
    int n, x, y;
    cin >> n;
    for (int i = 0; i < n; ++i) {
        g[i].clear();
    }
    pans.clear();
    for (int i = 0; i < n - 1; ++i) {
        cin >> x >> y;
        x--;
        y--;
        g[x].pb(y);
        g[y].pb(x);
    }
    dfs(0);
    for (auto i : pans) {
        cout << i << " ";
    }
    cout << '\n';
    return;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED