169 lines
3.5 KiB
C++
169 lines
3.5 KiB
C++
/* Problem URL: https://codeforces.com/contest/2134/problem/D */
|
|
|
|
#include <bits/stdc++.h>
|
|
#include <ext/pb_ds/assoc_container.hpp>
|
|
#include <ext/pb_ds/tree_policy.hpp>
|
|
|
|
using namespace std;
|
|
using namespace __gnu_pbds;
|
|
|
|
template <class T, class comp = less<>>
|
|
using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
|
|
|
|
#define V vector
|
|
|
|
#define rmin(a, b) a = min(a, b)
|
|
#define rmax(a, b) a = max(a, b)
|
|
|
|
#define rep(i, lim) for (int i = 0; i < (lim); i++)
|
|
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
|
|
|
|
#define repv(i, v) for (auto &i : (v))
|
|
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
|
|
#define sortv(v) sort(v.begin(), v.end())
|
|
#define all(v) (v).begin(), (v).end()
|
|
|
|
using vi = vector<int>;
|
|
using vvi = vector<vi>;
|
|
using vvvi = vector<vvi>;
|
|
using vvvvi = vector<vvvi>;
|
|
|
|
using ll = long long;
|
|
|
|
using vl = vector<ll>;
|
|
using vvl = vector<vl>;
|
|
using vvvl = vector<vvl>;
|
|
using vvvvl = vector<vvvl>;
|
|
|
|
template<class v>
|
|
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
|
|
os << vec[0];
|
|
for (size_t i = 1; i < vec.size(); i++) {
|
|
os << ' ' << vec[i];
|
|
}
|
|
os << '\n';
|
|
return os;
|
|
}
|
|
|
|
template<class v>
|
|
auto operator>>(istream &is, vector<v> &vec)->istream& {
|
|
for (auto &i : vec) {
|
|
is >> i;
|
|
}
|
|
return is;
|
|
}
|
|
|
|
template<class v>
|
|
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
|
|
for (auto &i : vec) {
|
|
os << i[0];
|
|
for (size_t j = 1; j < i.size(); j++) {
|
|
os << ' ' << i[j];
|
|
}
|
|
os << '\n';
|
|
}
|
|
return os;
|
|
}
|
|
|
|
template<class v>
|
|
auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
|
|
for (auto &i : vec) {
|
|
for (auto &j : i) {
|
|
is >> j;
|
|
}
|
|
}
|
|
return is;
|
|
}
|
|
|
|
int main()
|
|
{
|
|
ios::sync_with_stdio(false);
|
|
cin.tie(nullptr);
|
|
|
|
int t;
|
|
cin >> t;
|
|
while (t--) {
|
|
int n;
|
|
cin >> n;
|
|
|
|
if (n == 1) {
|
|
cout << "-1\n";
|
|
continue;
|
|
}
|
|
|
|
vvi graph(n);
|
|
|
|
rep(i, n - 1) {
|
|
int a, b;
|
|
cin >> a >> b;
|
|
a--, b--;
|
|
|
|
graph[a].push_back(b);
|
|
graph[b].push_back(a);
|
|
}
|
|
|
|
vi parent(n);
|
|
|
|
auto bfs = [&](int i) {
|
|
const int inf = INT32_MAX >> 1;
|
|
vi dis(n, inf);
|
|
queue<int> q;
|
|
|
|
dis[i] = 0;
|
|
q.push(i);
|
|
|
|
int ans = 0;
|
|
|
|
while (!q.empty()) {
|
|
i = q.front();
|
|
q.pop();
|
|
|
|
repv(j, graph[i]) {
|
|
if (dis[j] > dis[i] + 1) {
|
|
dis[j] = dis[i] + 1;
|
|
q.push(j);
|
|
ans = j;
|
|
parent[j] = i;
|
|
}
|
|
}
|
|
}
|
|
|
|
return ans;
|
|
};
|
|
|
|
int end1 = bfs(0);
|
|
fill(all(parent), -1);
|
|
int end2 = bfs(end1);
|
|
|
|
int a, b, c;
|
|
int p = end2;
|
|
int now = parent[end2];
|
|
|
|
bool pos = false;
|
|
|
|
while (parent[now] != -1 && !pos) {
|
|
repv(j, graph[now]) {
|
|
if (j == p || j == parent[now]) {
|
|
continue;
|
|
}
|
|
|
|
a = p;
|
|
b = now;
|
|
c = j;
|
|
pos = true;
|
|
break;
|
|
}
|
|
|
|
p = now;
|
|
now = parent[now];
|
|
}
|
|
|
|
if (pos) {
|
|
cout << a + 1 << ' ' << b + 1 << ' ' << c + 1 << '\n';
|
|
continue;
|
|
}
|
|
|
|
cout << "-1\n";
|
|
}
|
|
}
|