This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "simurgh.h"
#include <bits/stdc++.h>
using namespace std;
#define ll int
#define ff first
#define ss second
#define ln "\n"
#define ld long double
vector<pair<ll, ll>> e;
vector<vector<ll>> A;
ll n, m;
// slow version
vector<ll> ans;
void dfs(ll u, vector<bool> &vis, vector<ll> &cur, ll lev){
	vis[u]=1;
	if (lev==n){
		ll res=count_common_roads(cur);
		// cout << e[cur[0]].ff << " ";
		// for (auto ch:cur) cout << e[ch].ss << ' ';
		// cout << " : ";
		// cout << res << ln;
		if (res==n-1) {ans=cur; return;}
	}
	for (auto i:A[u]){
		ll v = e[i].ff^e[i].ss^u;
		if (!vis[v]){
			cur.push_back(i);
			dfs(v, vis, cur, lev+1);
			cur.pop_back();
			if (ans.size()) return;
		}
	}
	vis[u]=0;
}
vector<int> find_roads(int _n, vector<int> u, vector<int> v) {
	n=_n; m=u.size();
	e.resize(m); A.clear(); A.resize(n);
	for (ll i=0; i<m; i++){
		e[i]={u[i], v[i]};
		A[u[i]].push_back(i); A[v[i]].push_back(i);
	}
	vector<bool> vis(n);
	vector<ll> cur;
	for (ll i=0; i<n and !ans.size(); i++){
		vis.assign(n, 0); cur.clear();
		dfs(i, vis, cur, 1);
	}
	assert(ans.size());
	return ans;
}
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