下面是一个使用数据结构模拟ATM的示例代码，不使用数据库和文件处理。

class Account:
    def __init__(self, account_number, pin, balance):
        self.account_number = account_number
        self.pin = pin
        self.balance = balance

    def deposit(self, amount):
        self.balance += amount

    def withdraw(self, amount):
        if self.balance >= amount:
            self.balance -= amount
        else:
            print("Insufficient balance")

    def check_balance(self):
        return self.balance


class ATM:
    def __init__(self):
        self.accounts = {}

    def create_account(self, account_number, pin, initial_balance):
        if account_number in self.accounts:
            print("Account already exists")
            return
        account = Account(account_number, pin, initial_balance)
        self.accounts[account_number] = account
        print("Account created successfully")

    def authenticate(self, account_number, pin):
        if account_number in self.accounts:
            account = self.accounts[account_number]
            if account.pin == pin:
                return account
        print("Authentication failed")
        return None

    def deposit(self, account_number, amount):
        account = self.authenticate(account_number, pin)
        if account:
            account.deposit(amount)
            print("Deposit successful")
            return True
        return False

    def withdraw(self, account_number, pin, amount):
        account = self.authenticate(account_number, pin)
        if account:
            account.withdraw(amount)
            print("Withdrawal successful")
            return True
        return False

    def check_balance(self, account_number, pin):
        account = self.authenticate(account_number, pin)
        if account:
            balance = account.check_balance()
            print("Balance: ", balance)
            return balance
        return None


# 示例用法
atm = ATM()
atm.create_account("123456", "1234", 1000)  # 创建账户
atm.deposit("123456", 500)  # 存款
atm.withdraw("123456", "1234", 200)  # 取款
atm.check_balance("123456", "1234")  # 查询余额

该示例中使用了Account类来表示每个账户，其中包括账户号码、PIN码和余额。ATM类用于处理账户的创建、认证、存款、取款和查询余额等操作。ATM类使用字典类型来存储账户，其中键为账户号码，值为Account对象。