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。
 1 struct ListNode  //结点结构

 2 {

 3   int m_nValue;

 4   ListNode* m_pNext;

 5 };

 6 

 7 void DeleteNode(ListNode** pListHead , ListNode* pToBeDeleted)

 8 {

 9   if (!pListHead || !pToBeDeleted)

10   {

11     return;

12   }

13   if (pToBeDeleted->m_pNext != NULL)

14   {

15     ListNode* pNext = pToBeDeleted->m_pNext ;

16     pToBeDeleted->m_nValue = pNext->m_nValue;

17     pToBeDeleted->m_pNext = pNext->m_pNext;

18     delete pNext;

19     pNext = NULL;

20   }

21   else if (*pListHead == pToBeDeleted)//只有一个结点

22   {

23     delete pToBeDeleted;

24     pToBeDeleted = NULL;

25     *pListHead = NULL;

26   }

27   else //尾结点

28   {

29     ListNode* pNode = *pListHead ;

30     while (pNode->m_pNext != pToBeDeleted)

31     {

32       pNode = pNode->m_pNext;

33     }

34     pNode->m_pNext = NULL ;

35     delete pToBeDeleted;

36     pToBeDeleted = NULL ;

37   }

38 }

39 

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