数据结构基础(13) --链式栈的设计与实现

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:

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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:

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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:

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template <typename Type>

const Type &LinkStack<Type>::top() const

throw (std::out_of_range)

{

if (isEmpty())

throw std::out_of_range("stack is empty, can`t get data");

return m_top->data;

}

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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;

}

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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:

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template <typename Type>

void LinkStack<Type>::makeEmpty()

{

while (!isEmpty())

{

pop();

}

}

输出栈内所有内容:

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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:

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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;

}