题解 | 禁止重复注册

current_users=['Niuniu','Niumei','GURR','LOLO']
new_users=['GurR','Niu Ke Le','LoLo','Tuo Rui Chi']
s1=list(map(str.lower,current_users))
s2=list(map(str.lower,new_users))
for i in [0,1,2,3]:
    a=s2[i]
    if a in s1:
        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]))