HILLSEQ Hill Sequence - CodeChef Solution

t=int(input())
for _ in range(t):
    number=int(input())
    arr=list(map(int,input().split()))
    arrL,arrR,dic,maxx,maxx2=[],[],{},0,0
    for num in arr:
        if num in dic:
            dic[num]+=1
            arrL.append(num)
        else:
            dic[num]=1
            arrR.append(num)
        maxx=max(maxx,num)
    for k,v in dic.items():
        if v>2:
            maxx2=v
            break
    if dic[maxx]>1 or maxx2>2:
        print(-1)
    else:
        arrL.sort()
        arrR.sort(reverse=True)
        ans=arrL+arrR
        print(*ans)