python的题目 实在不会了 求大牛指点

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系统注册和模拟登录，将用户写成字典形式，可以试试如下代码：

users={'John':'Abc12345','Marry':'Mar11111','Tommy':'To123456'}
t=input('choice:register or login(r/l):')
if t=='r':
    name=input('username:')
    if name in  users:
        print('the user already exists!')
    else:
        
        psw=input('input password(numbers  or characters):')
        if all([x.isalnum() for x in psw]) and len(psw)==8:
            users.update({name:psw})
        else:
            print('invalid password.')
if t=='l':
    name=input('name:')
    psw=input('password:')
    if name in users:
        if psw==users[name]:
            print('login success!')
        else:
            print('password is wrong')
    else:
        print('Not found.')

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你题目的解答代码如下：（如有帮助，望采纳！谢谢! 点击我这个回答右上方的【采纳】按钮）

print('Python Supermarket checkout system')

name = input('name:')
price = float(input("price:"))
number = float(input("number:"))
due = price * number
print(f'The amount due:{due:.2f}')
rd = float(input("official receipts:"))
ch = rd - due*100//10/10
print(f'change:{ch:.2f}')

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li = ["非常满意","一般","满意","不满意","一般","满意","不满意","非常满意","一般","满意","满意","一般","满意","不满意","一般","满意","不满意","一般","满意","不满意","非常满意","一般","满意","不满意",]

d = {}
for v in li:
    d[v] = d.get(v,0) + 1
for k,v in d.items():
    print(f"{k}出现{v}次")
print(f"出现次数就多的是", max(d.keys(), key=lambda x: d[x]))
print(",".join(li))

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users = {'John':'Abc12345','Marry':'Mar11111','Tommy':'To123456'}
while True:
    print("菜单: 1.注册   2.登录   3.显示用户信息  4.退出")
    n=input("请输入1-4：")
    if n=='1':
        name = input('请输入用户名:')
        if name in users:
            print("该用户名已经存在！用户名不能重复！")
            continue
        password = input('请输入密码:')
        if not (password.isalnum() and len(password)==8):
            print("密码不符合要求,密码要求8位，包括英文大小写和数字")
            continue
        print("用户注册成功")
        users[name] = password

    elif n=='2':
        name = input('请输入用户名:')
        if name not in users:
            print("该用户名不存在！")
            continue
        password = input('请输入密码:')
        if users[name] != password:
            print("密码不正确")
            continue
        print("登录成功")
        break

    elif n=='3':
        for k,v in users.items():
            print(f'用户名:{k}\t\t密码:{v}')
    else:
        break

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