栈的概念及实现

Posted 2022-01-05 阿龙亡命天涯

栈的唯一特性：

//Stack.h
#ifndef STACK_H
#define STACK_H
#include "Object.h"
namespace DTLib

template < typename T >
class Stack : public Object

public:
    virtual void push(const T& e) = 0;
    virtual void pop() = 0;
    virtual T top() const = 0;
    virtual void clear() = 0;
    virtual int size() const = 0;
;

#endif // STACK_H

//StaticStack.h
#ifndef STATICSTACK_H
#define STATICSTACK_H
#include "Stack.h"
#include "Exception.h"
namespace DTLib

template < typename T, int N >
class StaticStack : public Stack<T>

protected:
    T m_space[N];
    int m_top;
    int m_size;
public:
    StaticStack()    // O(1)
    
        m_top = -1;
        m_size = 0;
    
    int capacity() const  // O(1)
    
        return N;
    
    void push(const T& e)  // O(1)
    
        if( m_size < N )
        
            m_space[m_top + 1] = e;
            m_top++;
            m_size++;
        
        else
        
            THROW_EXCEPTION(InvalidOperationException, "No space in current stack ...");
        
    
    void pop()   // O(1)
    
        if( m_size > 0 )
        
            m_top--;
            m_size--;
        
        else
        
            THROW_EXCEPTION(InvalidOperationException, "No element in current stack ...");
        
    
    T top() const   // O(1)
    
        if( m_size > 0 )
        
            return m_space[m_top];
        
        else
        
            THROW_EXCEPTION(InvalidOperationException, "No element in current stack ...");
        
    
    void clear()   // O(1)
    
        m_top = -1;
        m_size = 0;
    
    int size() const  // O(1)
    
        return m_size;
    
;

#endif // STATICSTACK_H

测试

抛异常，大小只有5，却加入10个元素





创建时，调用泛指类型的构造函数，效率很低
解决方案：



基于之前写的链表改写而成：

#ifndef LINKSTACK_H
#define LINKSTACK_H

#include "Stack.h"
#include "LinkList.h"

namespace DTLib


template < typename T >
class LinkStack : public Stack<T>

protected:
    LinkList<T> m_list;
public:
    void push(const T& e)  // O(1)
    
        m_list.insert(0, e);
    

    void pop()   // O(1)
    
        if( m_list.length() > 0 )
        
            m_list.remove(0);
        
        else
        
            THROW_EXCEPTION(InvalidOperationException, "No element in current stack ...");
        
    

    T top() const  // O(1)
    
        if( m_list.length() > 0 )
        
            return m_list.get(0);
        
        else
        
            THROW_EXCEPTION(InvalidOperationException, "No element in current stack ...");
        
    

    void clear()  // O(n)
    
        m_list.clear();
    

    int size() const  // O(1)
    
        return m_list.length();
    
;

#endif // LINKSTACK_H

输出1

输出0（多了个双引号）

小结：