题目描述：

模拟STL stack类设计实现你的stack类，该类需具有入栈，出栈，判栈空，取栈顶元素等功能；利用该类实现本题要求。本题要求使用单链表实现。不可使用STL stack类

输入描述：

分别构造两个空栈，再读入若干对整数v、x; 1<=v<=2; 将元素x入第v个栈 。

输出描述：

最后将两个栈中元素出栈，并输出；每个栈中元素占一行，元素间以空格分隔。

输入样例：

1 100
2 200
1 300
2 400
1 50
1 60
2 80

输出样例：

60 50 300 100
80 400 200
——————————————————————————————————————

代码：

#include <iostream>
using   namespace std;

class   CStack {
    struct Node {
        int data;
        Node *next;
    };
private :
    Node    *m_sp;

public :
    CStack  ()  :m_sp(NULL)   { //构造函数
    }
    CStack  (const CStack &rhs);//拷贝构造函数
    CStack & operator = (const CStack &rhs);//赋值运算符重载

    ~CStack ();              //析构函数
    void    push (int x);    //入栈
    bool    empty () const;  //判栈空
    int     top () const;    //取栈顶元素
    void    pop ();          //出栈
};

CStack::CStack  (const CStack &rhs) //拷贝构造函数
{
    m_sp = NULL;
    if (rhs.empty ()) //空栈？
        return;

    //复制链表首结点
    m_sp  = new Node;
    Node *q = rhs.m_sp;
    m_sp->data = q->data;

    //复制链表其余结点
    Node    *last = m_sp; //记录新链表最未结点
    q = q->next;
    while (q != NULL) {
        Node *p = new Node;
        p->data = q->data;//复制数据
        last->next = p; //新结点挂在新链表最后
        last = p;       //新结点成最后结点
        q = q->next;    //准备复制下一结点
    }
    last->next = NULL;  //最后结点指针置空
}

CStack & CStack::operator = (const CStack &rhs)//赋值运算符重载
{
    if (this == &rhs)
        return *this;
    this->~CStack ();  //析构自身

    m_sp = NULL;
    if (rhs.empty ()) //空栈？
        return *this; //返回自身

    //复制链表首结点
    m_sp  = new Node;
    Node *q = rhs.m_sp;
    m_sp->data = q->data;

    //复制链表其余结点
    Node    *last = m_sp; //记录新链表最未结点
    q = q->next;
    while (q != NULL) {
        Node *p = new Node;
        p->data = q->data;//复制数据
        last->next = p; //新结点挂在新链表最后
        last = p;       //新结点成最后结点
        q = q->next;    //准备复制下一结点
    }
    last->next = NULL;  //最后结点指针置空

    return *this;
}
CStack::~CStack ()
{
    while (m_sp != NULL) {
        Node *p = m_sp;
        m_sp = m_sp->next;
        delete p;
    }
}

void    CStack::push (int x)
{
    Node *p = new Node;
    p->data = x;
    p->next = m_sp;
    m_sp = p;
}

bool    CStack::empty () const
{
    return (m_sp == NULL);
}
int     CStack::top () const
{
    return m_sp->data;
}

void    CStack::pop ()
{
    Node *p = m_sp;
    m_sp = p->next;
    delete p;
}

int main()
{
    CStack  S1, S2;
    int v, x;

    while (cin >> v >> x) {
        if (v == 1)
            S1.push (x);
        else
            S2.push (x);
    }


    while (!S1.empty ()) {
        x = S1.top ();
        cout << x << " ";
        S1.pop ();
    }
    cout << endl;

    while (!S2.empty ()) {
        x = S2.top ();
        cout << x << " ";
        S2.pop ();
    }
    cout << endl;

    return 0;
}