#include<bits/stdc++.h>
using namespace std;
const int N = 6e5 + 10;
int a[N], pos[N], fa[N], pas[N], n;
inline void work(int c, int d){
    int st = c;
    for(int i = c; i <= d; ++i) pos[a[i]] = 0;
    int al = (d - c) / 2;
    for(int i = c; i <= d; ++i){
        if(a[i]){
            if(pos[a[i]]) --al;
            else pos[a[i]] = i, fa[a[i]] = a[i - 1];
        }
    }
    int now = a[c], p = 2; fa[now] = 2e9;
    for(int i = c; i <= d; ++i){
        if(!a[i]){
            while(p <= n && pas[p]) ++ p;
            if(al){
                if(fa[now] < p){
                    a[i] = now = fa[now], --al;
                }else{
                    fa[p] = now, a[i] = now = p; ++p;
                }
            }else{
                fa[p] = now, a[i] = now = p, ++p;
            }
        }else{
            now = a[i];
        }
    }
}
int main(){
    int T;
    scanf("%d", &T);
    while(T --){
        scanf("%d", &n);
        for(int i = 1; i <= n; ++i) pos[i] = fa[i] = pas[i] = 0;
        int m = n + n - 1;
        int al = n - 1;
        for(int i = 1; i <= m; ++i){
            scanf("%d", &a[i]);
            if(i == 1 || i == m) a[i] = 1;
            if(a[i]){
                if(pos[a[i]]) -- al;
                else pos[a[i]] = i;
                pas[a[i]] = i;
            }
        }
        int l = -1, r;
        for(int i = 2; i < m; ++i){
            if(!a[i]){
                l = i;
                for(int j = i; j < m; ++j){
                    if(!a[j]) r = j;
                    else break;
                }
                break;
            }
        }
        if(l != -1){
            if(pos[a[r + 1]] == r + 1){
                for(int i = 1; i <= n; ++i) pos[i] = 0;
                pos[1] = 1; fa[1] = 2e9;
                int now = 1, st = 2; a[1] = a[m] = 1;
                for(int i = 2; i < m; ++i){
                    if(a[i]){
                        if(!pos[a[i]]) fa[a[i]] = a[i - 1];
                        pos[a[i]] = i; now = a[i];
                    }else{
                        while(st <= n && pos[st]) ++st;
                        int po = st;
                        while(po <= n && al && fa[now] > po && pas[po] && (pas[po] - i) % 2 != 0){
                            ++po;
                            while(po <= n && pos[po]) ++po;
                            continue;
                        }
                        if(al){
                            if(fa[now] < po){
                                --al;
                                a[i] = now = fa[now];
                            }else{
                                fa[po] = now, a[i] = now = po; pos[po] = i;
                                if(pas[po]){
                                    work(i, pas[po]);
                                    break;
                                }
                                st += (po == st);
                            }
                        }else{
                            while(pas[st] && st <= n) ++st;
                            fa[st] = now, a[i] = now = st; ++st;
                        }
                    }
                }
            }else{
                work(pos[a[r + 1]], r + 1);
            }
        }
        for(int i = 1; i <= m; ++i) printf("%d ", a[i]);
        puts("");
    }
    return 0;
}