题解 | #禁止重复注册#

current_user = ['Niuniu', 'Niumei', 'GURR','LOLO']
new_users = ['GurR', 'Niu Ke Le', 'LoLo', 'Tuo Rui Chi']
cu = []
for c in current_user:
    c = c.lower()
    cu.append(c)
for user in new_users:
    user1 = user.lower()
    if user1 in cu:
        print(f"The user name {user} has already been registered! Please change it and try again!")
    else:
        print(f'Congratulations, the user name {user} is available!')