数据结构基础(13) --链式栈的设计与实现

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采用链式存储的栈成为链式栈(或简称链栈), 链栈的优点是便于多个栈共享存储空间和提高其效率, 且不存在栈满上溢的情况(因为链栈是靠指针链接到一起,只要内存够大, 则链栈理论上可以存储的元素是没有上限的);

与顺序栈相比, 由于顺序栈是采用的数组实现, 因此一旦数组填满, 则必须重新申请内存, 并将所有元素”搬家”, 而链栈则省略了这一”耗时耗力”的工作, 但却需要付出附加一个指针的代价;

链栈通常采用单链表实现, 并规定所有的操作都必须实在单链表的表头进行, 而且w我们的链栈没有头结点, m_top直接指向栈顶元素;

链式栈的图示如下:

链栈节点构造:

template <typename Type>class ChainNode{    template <typename T>    friend ostream &operator<<(ostream &os, const LinkStack<T> &stack);    friend class LinkStack<Type>;private:    ChainNode(const Type &_data, ChainNode *_next = NULL)        :data(_data), next(_next) {}    Type data;    ChainNode *next;};

链栈设计:

template <typename Type>class LinkStack{    template <typename T>    friend ostream &operator<<(ostream &os, const LinkStack<T> &stack);public:    LinkStack(): m_top(NULL) {}    ~LinkStack()    {        makeEmpty();    }    bool isEmpty() const    {        return m_top == NULL;    }    void pop() throw(std::out_of_range);    const Type &top() const throw(std::out_of_range);    void push(const Type &data);    void makeEmpty();private:    ChainNode<Type> *m_top;};

栈的三大操作:

template <typename Type>const Type &LinkStack<Type>::top() constthrow (std::out_of_range){    if (isEmpty())        throw std::out_of_range("stack is empty, can`t get data");    return m_top->data;}

template <typename Type>void LinkStack<Type>::pop()throw (std::out_of_range){    if (isEmpty())        throw std::out_of_range("stack is empty, can`t delete");    ChainNode<Type> *deleteNode = m_top;    m_top = m_top->next;    delete deleteNode;}

template <typename Type>void LinkStack<Type>::push(const Type &data){    //此处是整个链栈的关键点    // 该操作会生成一个节点,    // 并自动将m_top上移一格,    // 而且将m_top原先指向的节点, 作为新生成的节点的下一节点    //注意此处    //如果第一次运行push, 则原m_top为NULL    // 新m_top指向第一个元素    m_top = new ChainNode<Type>(data, m_top);}

清空整个栈:

template <typename Type>void LinkStack<Type>::makeEmpty(){    while (!isEmpty())    {        pop();    }}

输出栈内所有内容:

template <typename Type>ostream &operator<<(ostream &os, const LinkStack<Type> &stack){    ChainNode<Type> *currentNode = stack.m_top;    while (currentNode != NULL)    {        cout << currentNode->data << ' ';        currentNode = currentNode->next;    }    return os;}

测试代码:

int main(){    LinkStack<int> test;    for (int i = 0; i < 10; ++i)    {        test.push(rand()%100);    }    cout << test << endl;    cout << "top = " << test.top() << endl;    test.pop();    cout << "top = " << test.top() << endl;    test.push(1);    cout << "top = " << test.top() << endl;    while (!test.isEmpty())    {        test.pop();    }    cout << test << endl;    test.push(11);    test.push(22);    test.push(33);    cout << test << endl;    test.makeEmpty();    try    {        cout << "top = " << test.top() << endl;    }    catch (const std::exception &e)    {        cerr << e.what() << endl;    }    return 0;}

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