题解 | #禁止重复注册#

current_users = ["Niuniu", "Niumei", "GURR", "LOLO"]
new_users = ["GurR", "Niu Ke Le", "LoLo", "Tuo Rui Chi"]
current_users = [_.lower() for _ in current_users]

for i in new_users:
    if i.lower() in current_users:
        print(
            f"The user name {i} has already been registered! Please change it and try again!"
        )
    else:
        print(f"Congratulations, the user name {i} is available!")