面试题21 包含min函数的栈

CStack.h:

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#pragma once

class CStackElement

{

public:

CStackElement(void){}

CStackElement(int data, int min=0)

{

m_nData = data;

m_nMin = min;

}

~CStackElement(void){}

public:

int m_nData;

int m_nMin;

};

class CStack

{

public:

CStack(int maxSize);//普通构造函数，构造一个大小为maxSize的栈

CStack(const CStack &stack);//拷贝构造函数

CStack & operator=(const CStack &stack);//赋值函数

~CStack(void);

void Push(int nPushElement);//向栈中压入一个元素nElement

void Pop();//从栈中弹出一个元素，并返回

int Min();//O(1)的时间返回最小元素值

private:

CStackElement *m_pStackArr;

int m_top;//指向栈顶元素的下一个位置

int m_nMaxSize;

};

CStack.cpp:

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#include "StdAfx.h"

#include "CStack.h"

#include <iostream>

using namespace std;

//普通构造函数，构造一个大小为maxSize的栈

CStack::CStack(int maxSize)

{

m_top = 0;//指向栈顶元素的下一个位置

m_nMaxSize = maxSize;

m_pStackArr = new CStackElement[m_nMaxSize];

}

//拷贝构造函数

CStack::CStack(const CStack &stack)

{

m_top = stack.m_top;

m_nMaxSize = stack.m_nMaxSize;

m_pStackArr = new CStackElement[m_nMaxSize];

memcpy(m_pStackArr, stack.m_pStackArr, m_nMaxSize);

}

//赋值函数

CStack & CStack::operator=(const CStack &stack)

{

if (this == &stack)//自赋值检查

{

return *this;

}

if (stack.m_top != 0)//stack为空

{

if (m_nMaxSize < stack.m_nMaxSize)

{

m_nMaxSize = stack.m_nMaxSize;

delete [] m_pStackArr;

m_pStackArr = new CStackElement[m_nMaxSize];

memcpy(m_pStackArr, stack.m_pStackArr, m_nMaxSize);

}

}

return *this;

}

//向栈中压入一个元素nElement

void CStack::Push(int nPushElement)

{

if (m_top == m_nMaxSize)

{

cout << "栈满！" << endl;

}

else if (m_top == 0)//栈空

{

m_pStackArr[m_top++].m_nData = nPushElement;

m_pStackArr[m_top++].m_nMin = nPushElement;

cout << "压入" << nPushElement<< endl;

}

else

{

if (m_pStackArr[m_top-1].m_nMin > nPushElement)

{

m_pStackArr[m_top].m_nMin = nPushElement;

}

else

{

m_pStackArr[m_top].m_nMin = m_pStackArr[m_top-1].m_nMin;

}

m_pStackArr[m_top++].m_nData= nPushElement;

cout << "压入" << nPushElement<< endl;

}

}

//从栈中弹出一个元素，并返回

void CStack::Pop()

{

int nPopElement = 0;

if (m_top == 0)

{

nPopElement = -1;

cout << "栈空！" << endl;

}

else

{

nPopElement = m_pStackArr[--m_top].m_nData;

cout << "弹出" << nPopElement << endl;

}

}

//O(1)的时间返回最小元素值

int CStack::Min()

{

if (m_top == 0)

{

cout << "栈空！" << endl;

return -1;

}

else

{

return m_pStackArr[m_top-1].m_nMin;

}

}

CStack::~CStack(void)

{

}

测试代码：

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// 栈和队列的灵活应用一：包含min,max函数的栈.cpp : 定义控制台应用程序的入口点。

//

#include "stdafx.h"

#include <iostream>

#include "CStack.h"

using namespace std;

int _tmain(int argc, _TCHAR* argv[])

{

CStack stack(20);

stack.Push(4);

cout << "Min: " << stack.Min() << endl;

stack.Push(5);

cout << "Min: " << stack.Min() << endl;

stack.Push(2);

cout << "Min: " << stack.Min() << endl;

stack.Pop();

cout << "Min: " << stack.Min() << endl;

stack.Push(3);

cout << "Min: " << stack.Min() << endl;

system("pause");

return 0;

}