T=int(input())
for t in range(T):
    N=int(input())
    A=list(map(int,input().split()))
    for i in range(2*N-1):
        A[i]-=1
    def solve(A):
        if A[0]==-1:
            A[0]=0
        if A[-1]==-1:
            A[-1]=0
        if not -1 in A:
            return A
        parents=[None]*N
        seen=[0]*N
        for a in A:
            if a>=0:
                seen[a]=1
        idx=[i for i in range(2*N-1) if A[i]==-1]
        for a,b in zip(A,A[1:]):
            if b==-1:
                break
            if a==0:
                parents[b]=a
            elif b==0:
                parents[a]=b
            else:
                if parents[b]==None:
                    parents[b]=a
        for a,b in zip(A[::-1],A[::-1][1:]):
            if b==-1:
                break
            if a==0:
                parents[b]=a
            elif b==0:
                parents[a]=b
            else:
                if parents[b]==None:
                    parents[b]=a
        tour0=[A[idx[0]-1]]
        tour1=[A[idx[-1]+1]]
        while parents[tour0[-1]]!=None:
            tour0.append(parents[tour0[-1]])
        while parents[tour1[-1]]!=None:
            tour1.append(parents[tour1[-1]])
        while tour0 and tour1 and tour0[-1]==tour1[-1]:
            lca=tour0.pop()
            tour1.pop()
        tour=tour0+[lca]+tour1[::-1]
        queue=[x for x in range(N-1,-1,-1) if not seen[x]]
        le=len(tour)
        i=0
        x=tour[0]
        lst=[]
        while i<le-1 or queue:
            if tour[i]==x:
                if i==le-1:
                    parents[queue[-1]]=x
                    x=queue.pop()
                elif not queue:
                    i+=1
                    x=tour[i]
                elif tour[i+1]<queue[-1]:
                    i+=1
                    x=tour[i]
                else:
                    parents[queue[-1]]=x
                    x=queue.pop()
            else:
                if not queue:
                    x=parents[x]
                elif parents[x]<queue[-1]:
                    x=parents[x]
                else:
                    parents[queue[-1]]=x
                    x=queue.pop()
            lst.append(x)
        for i,x in zip(idx,lst):
            A[i]=x
        return A
    ans_lst=solve(A)
    print(*[ans+1 for ans in ans_lst])