面试题13：在O(1)时间删除链表节点

注意分情况讨论：

1. 要删除的不是尾节点

2. 链表只有一个节点

3. 链表中有多个节点，删除尾节点

 void DeleteNode(ListNode** pListHead, ListNode* pToBeDeleted)
 {
     if(!pListHead || !pToBeDeleted)
         return;

     // 要删除的结点不是尾结点
     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，删除头结点（也是尾结点）
     else if(*pListHead == pToBeDeleted)
     {
         delete pToBeDeleted;
         pToBeDeleted = NULL;
         *pListHead = NULL;
     }
     // 链表中有多个结点，删除尾结点
     else
     {
         ListNode* pNode = *pListHead;
         while(pNode->m_pNext != pToBeDeleted)
         {
             pNode = pNode->m_pNext;
         }

         pNode->m_pNext = NULL;
         delete pToBeDeleted;
         pToBeDeleted = NULL;
     }
 }