CF2110E 测评机：wrong answer, Jury found answer, but participant didn't (test case 103)

#include<bits/stdc++.h>
#define YES cout<<"YES\n"
#define NO cout<<"NO\n"
#define Yes cout<<"Yes\n"
#define No cout<<"No\n"
#define endl "\n"
#define mpr make_pair
#define pb push_back
#define all(x) x.begin(),x.end()
#define sz(v) (int)v.size()

using namespace std;

typedef long double ld;
typedef long long ll;
typedef pair<int,int> pii;

const int inf=2e9;
const int MOD=998244353;
const int maxn=200005;
map<int,int> L,R;
vector<pii> g[maxn<<1];
bool used[maxn];
vector<int> ans;
void dfs(int v){
	for(pii x:g[v]){
		if(!used[x.second]){
			
			ans.pb(x.second);
			used[x.second]=true;
			dfs(x.first);
			break;
		}
	}
}
void solve(){
	int n;
	cin>>n;
	L.clear(); R.clear();
	ans.clear();
	for(int i=1;i<=2*n;i++){
		g[i].clear();
	}
	for(int i=1;i<=n;i++){
		used[i]=false;
	}
	int cnt=0;
	for(int i=1;i<=n;i++){
		int x,y;
		cin>>x>>y;
		if(!L[x]) L[x]=++cnt;
		x=L[x];
		if(!R[y]) R[y]=++cnt;
		y=R[y];
		g[x].pb(mpr(y,i));
		g[y].pb(mpr(x,i));
	}
	for(int i=1;i<=cnt;i++){
		if(sz(g[i])&1){
			dfs(i);
			break;
		}
	}
	if(sz(ans)==0){
		dfs(1);
	}
	if(sz(ans)!=n){
		NO;
		return;
	}
	for(int i=1;i<=n;i++){
		if(!used[i]){
			NO;
			return;
		}
	}
	YES;
	for(int x:ans){
		cout<<x<<" ";
	}
	cout<<endl;
}

int32_t main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

	int32_t T=1;
	cin>>T;
	while(T--){
		solve();
	}
	return 0;
}