面试题14：反转链表

代码：

#include "stdafx.h"
#include <iostream>
using namespace std;

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

ListNode *ReverseList(ListNode *pListHead)
{
	if (pListHead == NULL)
	{
		return NULL;
	}

	ListNode *pReverseHead = NULL;
	ListNode *pPre = NULL;
	ListNode *pNode = pListHead;
	ListNode *pNext = NULL;

	while (pNode != NULL)
	{
       pNext = pNode->m_pNext;
	   if (pNext == NULL)
	   {
		   pReverseHead = pNode;		   
	   }
	   pNode->m_pNext = pPre;
	   pPre = pNode;
	   pNode = pNext;
	}
	return pReverseHead;
}

//创建一个链表，输入从头到尾结点的值，输入-1表示结束
void CreateList(ListNode *& pHead)
{	
	ListNode *pListNode = NULL;
	ListNode *pCurLastNode = NULL;
	bool isHead = true;

	while (1)
	{
		if (isHead)
		{	
			pHead = new ListNode();
			cin >> pHead->m_nValue;
			pHead->m_pNext = NULL;
			isHead = false;
			pCurLastNode = pHead;
		}
		else
		{
			pListNode = new ListNode();
			cin >> pListNode->m_nValue;
			if (pListNode->m_nValue == -1)
			{
				break;
			}
			pListNode->m_pNext = NULL;
			pCurLastNode->m_pNext = pListNode;
			pCurLastNode = pListNode;	
		}			
	}
}

//从头到尾打印链表
void PrintList(ListNode *&pHead)
{
	if (pHead != NULL)
	{
		ListNode *pCur = pHead;
		while (pCur != NULL)
		{
			cout << pCur->m_nValue << " ";
			pCur = pCur->m_pNext;
		}
		cout << endl;
	}
	else
	{
		cout << "链表为空！" << endl;
	}
}

int _tmain(int argc, _TCHAR* argv[])
{
	ListNode *pListHead = NULL;
	CreateList(pListHead);
	PrintList(pListHead);
	ListNode *pReverseHead = ReverseList(pListHead);
	cout << pReverseHead->m_nValue << endl;
	PrintList(pReverseHead);
    system("pause");
	return 0;
}