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