#include "bits/stdc++.h"
using namespace std;
using ll = long long;
ll MOD = 1000000007;
ll INF = (1ll<<30);
#define rep(i,n) for(int i=0;i<n;i++)

int main(){
    ll t;
    cin >> t;
    rep(_, t){
        ll n;
        cin >> n;
        ll m = 2*n-1;
        vector<ll> v(m);
        rep(i, m) cin >> v[i];
        rep(i, m) v[i]--;
        ll a = 0, b = m-1;
        v[0] = 0;
        v[m-1] = 0;
        
        while(a<m && v[a]!=-1) a++;
        while(b>=0 && v[b]!=-1) b--;
        if(a == m){
            for(auto x:v) cout << x+1 << " ";
            cout << endl;
            continue;
        }
        vector<ll> par(n, -1);
        rep(i, a-1) if(par[v[i+1]] == -1) par[v[i+1]] = v[i];
        for(ll i=m-1; i>b+1; i--) if(par[v[i-1]] == -1) par[v[i-1]] = v[i];
        ll sza = 0, szb = 0;
        ll na = v[a-1], nb = v[b+1];
        while(na!=0){
            sza ++;
            na = par[na];
        }
        while(nb!=0){
            szb++;
            nb = par[nb];
        }
        vector<ll> vv;
        vector<ll> ww;
        na = v[a-1], nb = v[b+1];
        while(na!=nb){
            if(sza >= szb){
                vv.emplace_back(na);
                na = par[na];
                sza--;
            }else{
                ww.emplace_back(nb);
                nb = par[nb];
                szb--;
            }
        }
        vv.emplace_back(na);
        while(!ww.empty()){
            vv.emplace_back(ww.back());
            ww.pop_back();
        }
        vector<ll> chk(n+3, 0);
        for(auto x:v) if(x!=-1) chk[x] = 1;
        ll nx = 0;
        while(chk[nx]) nx++;
        stack<ll> stk;
        while(!vv.empty()){
            stk.push(vv.back());
            vv.pop_back();
        }
        ll nd = stk.top();
        stk.pop();
        
        for(ll i=a; i<=b; i++){
            while(chk[nx]) nx++;
            ll p;
            if(stk.empty()) p = n+2;
            else p = stk.top();
            if(p < nx){
                stk.pop();
                chk[p] = 1;
                v[i] = p;
                nd = p;
            }else{
                stk.push(nd);
                nd = nx;
                chk[nx] = 1;
                v[i] = nx;
            }
        }
        for(auto x:v) cout << x+1 << " ";
        cout << endl;


        
    }
}