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

使用了列表推导式