/*
	Brief:反转链表
*/

#include "stdafx.h"
#include "list.h"

ListNode *ReverseList(ListNode *pHead)
{
	ListNode *pReversedHead = NULL;
	ListNode *pNode = pHead;
	ListNode *pPrev = NULL;

	while(pNode != NULL)
	{
		ListNode *pNext = pNode->m_pNext;
		if(pNext == NULL)
			pReversedHead = pNode;
		pNode->m_pNext = pPrev;
		pPrev = pNode;
		pNode = pNext;
	}
	return pReversedHead;
}

// ====================测试代码====================
ListNode *Test(ListNode* pHead)
{
	printf("The original list is: \n");
	PrintList(pHead);

	ListNode *pReversedHead = ReverseList(pHead);

	printf("The reversed list is: \n");
	PrintList(pReversedHead);

	return pReversedHead;
}

// 输入的链表有多个结点
void Test1()
{
	ListNode* pNode1 = CreateListNode(1);
    ListNode* pNode2 = CreateListNode(2);
    ListNode* pNode3 = CreateListNode(3);
    ListNode* pNode4 = CreateListNode(4);
    ListNode* pNode5 = CreateListNode(5);

	ConnectListNodes(pNode1, pNode2);
    ConnectListNodes(pNode2, pNode3);
    ConnectListNodes(pNode3, pNode4);
    ConnectListNodes(pNode4, pNode5);

	ListNode* pReversedHead = Test(pNode1);
	DestroyList(pReversedHead);
}

// 输入的链表只有一个结点
void Test2()
{
	ListNode* pNode1 = CreateListNode(1);

	ListNode* pReversedHead = Test(pNode1);

	DestroyList(pReversedHead);
}

// 输入空链表
void Test3()
{
    Test(NULL);
}

int _tmain(int argc ,_TCHAR *argv[])
{
	Test1();
	Test2();
	Test3();

	return 0;
}

struct ListNode
{
	int m_nKey;
	ListNode *m_pNext;
};

__declspec(dllexport)ListNode *CreateListNode(int value);
__declspec(dllexport)void ConnectListNodes(ListNode *pCurrent, ListNode *pNext);
__declspec(dllexport)void PrintList(ListNode *pHead);
__declspec(dllexport)void DestroyList(ListNode *pHead);

#include "list.h"
#include <stdio.h>
#include <stdlib.h>

ListNode  *CreateListNode(int value)
{
	ListNode *pNode = new ListNode();
	pNode->m_nKey = value;
	pNode->m_pNext = NULL;
	
	return pNode;
}

void ConnectListNodes(ListNode *pCurrent, ListNode *pNext)
{
	if(pCurrent == NULL)
	{
		printf("Error to connect two nodes.\n");
        exit(1);	// exit(1)表示异常退出.这个1是返回给操作系统的。
	}
	pCurrent->m_pNext = pNext;
}

void PrintList(ListNode *pHead)
{
	printf("PrintList starts.\n");
	ListNode *pNode = pHead;
	while(pNode != NULL)
	{
		printf("%d\t", pNode->m_nKey);
		pNode = pNode->m_pNext;
	}
}

void DestroyList(ListNode *pHead)
{
	ListNode *pNode = pHead;
	while(pNode != NULL)
	{
		pHead = pHead->m_pNext;
		delete pNode;
		pNode = pHead;
	}
}