📑 Farewell Round A 2023 Task 3 Rainbow Sort

Farewell Round A 2023. Task 3

Python Only

# Competition Variant 1 (All Points)
T=int(input())
for t in range(T):
    N=int(input())
    cards=input().split()
    cards_set=set()
    result=[]
    for i in range(N):
        if cards[i] not in cards_set:
            cards_set.update([cards[i]])
            result.append(cards[i])
        elif result[-1]!=cards[i]:
            result='IMPOSSIBLE'
            break
 #       print(i,result)
    if result!='IMPOSSIBLE': result=' '.join(result)
    print('Case #{}: {}'.format((t+1),result))