请使用C++写一个动态链表，要求链表的结点由三种类，teacher，worker，leader三种类混合而成，根据数据输入的1，2，3来决定构建什么类，且这三种类都由基类employ构成，指针next也存在于基类中

以下是一个简单的动态链表代码，其中包含三种类：Teacher、Worker和Leader，都是由Employ类继承而来。

#include <iostream>
#include <string>

using namespace std;

class Employ {
public:
    string name;
    int age;
    Employ* next; // 指向下一个节点的指针

    Employ(string name, int age) {
        this->name = name;
        this->age = age;
        next = NULL;
    }

    virtual void display() {
        cout << "Name: " << name << ", Age: " << age << endl;
    }
};

class Teacher : public Employ {
public:
    string course;

    Teacher(string name, int age, string course) : Employ(name, age) {
        this->course = course;
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << ", Course: " << course << endl;
    }
};

class Worker : public Employ {
public:
    string job;

    Worker(string name, int age, string job) : Employ(name, age) {
        this->job = job;
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << ", Job: " << job << endl;
    }
};

class Leader : public Employ {
public:
    string department;

    Leader(string name, int age, string department) : Employ(name, age) {
        this->department = department;
    }

    void display() {
        cout << "Name: " << name << ", Age: " << age << ", Department: " << department << endl;
    }
};

int main() {
    Employ* head = NULL;
    while (true) {
        int choice;
        cout << "Please input 1 for Teacher, 2 for Worker, 3 for Leader, 0 to exit: ";
        cin >> choice;
        if (choice == 0) {
            break;
        }

        string name;
        int age;
        cout << "Please input name: ";
        cin >> name;
        cout << "Please input age: ";
        cin >> age;

        Employ* emp;
        switch (choice) {
            case 1: {
                string course;
                cout << "Please input course: ";
                cin >> course;
                emp = new Teacher(name, age, course);
                break;
            }
            case 2: {
                string job;
                cout << "Please input job: ";
                cin >> job;
                emp = new Worker(name, age, job);
                break;
            }
            case 3: {
                string department;
                cout << "Please input department: ";
                cin >> department;
                emp = new Leader(name, age, department);
                break;
            }
            default:
                cout << "Invalid choice!" << endl;
                continue;
        }

        if (head == NULL) {
            head = emp;
        } else {
            Employ* current = head;
            while (current->next != NULL) {
                current = current->next;
            }
            current->next = emp;
        }
    }

    Employ* current = head;
    while (current != NULL) {
        current->display();
        current = current->next;
    }

    return 0;
}