Distances

#include <bits/stdc++.h>
using namespace std;

constexpr int MAXN = 5+100;
vector<int> t[MAXN];
int pa[MAXN];

void dfs1(int u) {
  for (int v : t[u]) {
    if (v == pa[u]) continue;
    pa[v] = u;
    dfs1(v);
  }
}

void dfs2(int u) {
  cout << u << ' ';
  for (int v : t[u]) {
    for (int w : t[v]) {
      dfs2(w);
    }
    cout << v << ' ';
  }
}

int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
  int tc; cin >> tc;
  while (tc--) {
    int n; cin >> n;
    for (int i = 0; i < MAXN; ++i) {
      t[i].clear();
      pa[i] = -1;
    }
    for (int i = 0; i < n-1; ++i) {
      int a,b; cin >> a >> b;
      t[a].push_back(b);
      t[b].push_back(a);
    }
    dfs1(1);
    for (int i = 2; i <= n; ++i) {
      t[i].erase(find(t[i].begin(), t[i].end(), pa[i]));
    }
    dfs2(1);
    cout << '\n';
  }
  return 0;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED