單鏈表逆置

題目：輸入一個單向鏈表，將該單鏈表逆置。

舉例：原來鏈表為1->2->3->4->5翻轉為5->4->3->2->1

鏈表結點定義如下：

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

答：

#include "stdafx.h"
#include <iostream>
#include <fstream>

using namespace std;

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

//構造鏈表
void CreateList(ListNode *&pHead)
{
    fstream fin("list.txt");
    ListNode *pNode = NULL;
    ListNode *pTmp = NULL;
    int data;
    fin>>data;
    while (data)
    {
        pNode = new ListNode;
        pNode->m_nKey = data;
        pNode->m_pNext = NULL;
        if (NULL == pHead)
        {
            pHead = pNode;
            pTmp = pNode;
        }
        else
        {
            pTmp->m_pNext = pNode;
            pTmp = pNode;
        }

        fin>>data;
    }
}

//翻轉單鏈表
void ReverseLink(ListNode *&pHead)
{
    if (NULL == pHead)
    {
        return;
    }
    ListNode *pNode = pHead;
    ListNode *Prev = NULL;
    ListNode *pNext = NULL;
    while (NULL != pNode)
    {
        pNext = pNode->m_pNext;
        if (NULL == pNext)
        {
            pHead = pNode;
        }
        pNode->m_pNext = Prev;
        Prev = pNode;
        pNode = pNext;
    }
}

void PrintList(ListNode *pHead)
{
    if (NULL == pHead)
    {
        return;
    }
    ListNode *pNode = pHead;
    while (NULL != pNode)
    {
        cout<<pNode->m_nKey<<"  ";
        pNode = pNode->m_pNext;
    }
    cout<<endl;
}

int _tmain(int argc, _TCHAR* argv[])
{
    ListNode *pHead = NULL;
    cout<<"原來的鏈表：";
    CreateList(pHead);
    PrintList(pHead);
    ReverseLink(pHead);
    cout<<"翻轉的鏈表：";
    PrintList(pHead);

    return 0;
}

運行界面如下：

建造鏈表的list.txt文件如下：

12 11 10 9 8 7 6 5 4 3 2 1 0