题解 | #禁止重复注册#

current_users = ['Niuniu', 'Niumei', 'GURR', 'LOLO']
new_users = ['GurR', 'Niu Ke Le', 'LoLo', 'Tuo Rui Chi']

# 将 current_users 转换为小写的集合，以便进行不区分大小写的比较
lowercase_current_users = {user.lower() for user in current_users}

for i in new_users:
    if i.lower() in lowercase_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!")