//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

 {

   int m_nValue;

   ListNode* m_pNext;

 };

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

 {

   if (!pListHead || !pToBeDeleted)

   {

     return;

   }

   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;

   }

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

   {

23     delete pToBeDeleted;

     pToBeDeleted = NULL;

     *pListHead = NULL;

   }

   else //尾结点

   {

     ListNode* pNode = *pListHead ;

     while (pNode->m_pNext != pToBeDeleted)

     {

       pNode = pNode->m_pNext;

     }

     pNode->m_pNext = NULL ;

     delete pToBeDeleted;

     pToBeDeleted = NULL ;

   }

 }