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