题解 | #禁止重复注册#

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

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