#include <bits/stdc++.h>

using namespace std;

#define int long long
#define forn(i,n) for(int i = 0; i <(int)n; ++i)
#define vi vector<int>
#define debug(x)    cout << #x << " : " << x << endl;

const int MOD = 1000000007;
//const int MOD = 998244353;

int n;

int peek(stack<int>& st, int x) {
    stack<int> tmp;
    forn(i, x-1) {
        tmp.push(st.top());
        st.pop();
    }
    int ans = st.top();
    while (!tmp.empty()) {
        st.push(tmp.top());
        tmp.pop();
    }
    return ans;
}

int peek(vi& v, int x) {
    return v[v.size() - x];
}

void init() {
    
}

void solve() {
    cin >> n;
    init();

    vi udah(n+5);
    vi vec(2*n-1);
    forn(i, 2*n-1) {
        cin >> vec[i];
        vec[0] = vec[2*n-2] = 1;
    }
    stack<int> st, en;

    forn(i, 2*n-1) {
        udah[vec[i]] = 1;
        if (vec[i] == 0) break;
    }

    forn(i, 2*n-1) {
        if (vec[i] == 0) break;
        if (st.size() >= 2 && peek(st, 2) == vec[i]) {
            st.pop();
        }
        else {
            st.push(vec[i]);
        }
    }

    for (int i = 2*n-2; i >= 0; i--) {
        if (vec[i] == 0) break;
        if (en.size() >= 2 && peek(en, 2) == vec[i]) {
            en.pop();
        }
        else {
            en.push(vec[i]);
        }
    }


    vi stv, env;

    while (!st.empty()) {
        stv.push_back(st.top());
        st.pop();
    }
    reverse(stv.begin(), stv.end());
    while (!en.empty()) {
        env.push_back(en.top());
        en.pop();
    }
    reverse(env.begin(), env.end());

    vi posen(n+5, -1);
    forn(i, env.size()) {
        posen[env[i]] = i;
    }


    
    // cout << "\n\n\n";
    // forn(i, stv.size()) cout << stv[i] << ' '; cout << endl;
    // forn(i, env.size()) cout << env[i] << ' '; cout << endl;

    set<int> havent;
    forn(i, n) {
        if (!udah[i+1]) havent.insert(i+1);
    }
    int nx = 0;
    for (int i  = 0; i < stv.size() && i < env.size(); i++) {
        if (stv[i] == env[i]) {
            nx++;
        }
        else {
            break;
        }
    }

    forn(i, 2*n-1) {
        if (vec[i] == 0) {
            if (nx < stv.size() && stv.size() >= 2) {
                // boleh pop | push
                int peekval = peek(stv, 2);
                int pushval;
                if (havent.empty()) pushval = LLONG_MAX;
                for (auto pp: havent) {
                    if (posen[pp] == -1 || posen[pp] == stv.size()) {
                        pushval = pp;
                        break;
                    }
                }




                if (peekval < pushval) {
                    stv.pop_back();
                    vec[i] = peekval;
                }
                else {
                    stv.push_back(pushval);
                    vec[i] = pushval;
                    havent.erase(pushval);
                }
            }
            else {
                // boleh push doang (+ cek di bawah)
                int pushval = *havent.begin();
                stv.push_back(pushval);
                vec[i] = pushval;
                havent.erase(pushval);
            }

            while (nx < stv.size() && nx < env.size() && stv[nx] == env[nx]) {
                nx++;
            }
        }
    }

    forn(i, 2*n-1) {
        cout << vec[i] << ' ';
    }cout << '\n';


}

int32_t main()
{
    ios::sync_with_stdio(false); cin.tie(NULL);
    int tc = 1;
    cin >> tc;
    while(tc--) {
        solve();
    }
    return 0;
}