异质链表的实现。实现异质链表的查找、插入、删除和遍历。面向对象编程，类，多态，继承，虚函数，虚析构函数，内存泄露 -Heterogeneous linked list implementation. Find heterogeneous linked list to achieve, insert, delete, and traverse. Object-oriented programming, classes, polymorphism, inheritance, virtual fu