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 = [user.lower() for user in current_users]
# 遍历新用户列表，逐个检查用户名是否已注册
for user in new_users:
    # 将当前遍历的新用户名转为小写
    user_lower = user.lower()
    if user_lower in current_users_lower:
        # 用户名已存在，输出提示
        print(f'The user name {user} has already been registered! Please change it and try again!')
    else:
        # 用户名可用，输出提示
        print(f'Congratulations, the user name {user} is available!')