在O(1) 时间删除链表结点

#include "stdafx.h"
#include <iostream>
/*
题目:在O(1)时间删除链表结点
    给定单向链表的头指针和一个结点指针，定义一个函数在O(1)时间删除该结点。链表结点与函数定义如下:
    struct ListNode
    {
        int m_nValue;
        ListNode *m_pNext;
    };
    void DeleteNode(ListNode** pListHead,ListNode* pToBeDeleted);
*/
using namespace std;
struct ListNode
    {
        int m_nValue;
        ListNode *m_pNext;
    };
void DeleteNode(ListNode** pListHead,ListNode* pToBeDeleted)
{
    if (pListHead ==NULL||pToBeDeleted==NULL)
    {
        return;
    }
    //删除的不是尾结点
    if(pToBeDeleted->m_pNext!=NULL)
    {
        ListNode* pNext = pToBeDeleted->m_pNext;
        pToBeDeleted->m_nValue=pNext->m_nValue;
        pToBeDeleted->m_pNext=pNext->m_pNext;
        delete pNext;
        pNext=NULL;
    }
    //链表只有一个结点
    else if(*pListHead==pToBeDeleted)
    {
        delete pToBeDeleted;
        pToBeDeleted=NULL;
        *pListHead = NULL;
    }
    //如果要删除的是尾结点
    else
    {
        ListNode* pNode = *pListHead;
        while(pNode->m_pNext!=pToBeDeleted)
            pNode=pNode->m_pNext;
        pNode->m_pNext = NULL;
        delete pToBeDeleted;
        pToBeDeleted=NULL;
    }
}


int _tmain(int argc, _TCHAR* argv[])
{ 
    
    return 0 ;
}