在O(1)时间删除链表结点

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

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

  1 #include<iostream>
  2 #include<stdlib.h>
  3 using namespace std;
  4 
  5 //链表结构 
  6 struct ListNode
  7 {
  8     int m_nValue;
  9     ListNode* m_pNext;
 10 };
 11 
 12 //创建一个链表结点 
 13 ListNode* CreateListNode(int value)
 14 {
 15     ListNode *pNode = new ListNode();
 16     pNode->m_nValue=value;
 17     pNode->m_pNext=NULL;
 18     return pNode;
 19     
 20 }
 21 
 22 //遍历链表中所有结点
 23 void PrintList(ListNode* pHead)
 24 {
 25     ListNode *pNode = pHead;
 26     while(pNode!=NULL)
 27     {
 28         cout<<pNode->m_nValue<<" ";
 29         pNode=pNode->m_pNext;
 30     }
 31     cout<<endl;
 32 }
 33 //连接两个结点 
 34 void ConnectListNode(ListNode *pCurrent,ListNode* pNext)
 35 {
 36     if(pCurrent==NULL)
 37     {
 38         cout<<"前一个结点不能为空"<<endl;
 39         exit(1);
 40     }
 41     else
 42     {
 43         pCurrent->m_pNext=pNext;
 44     }
 45 }
 46 
 47 //删除链表 
 48 void DestroyList(ListNode* pHead)
 49 {
 50     ListNode* pNode = pHead;
 51     while(pNode != NULL)
 52     {
 53         pHead = pHead->m_pNext;
 54         delete pNode;
 55         pNode = pHead;
 56     }
 57 }
 58 
 59 
 60 
 61       
 62 //考虑四种不同的情况   
 63 void DeleteNode(ListNode** pListHead, ListNode* pTobeDeleted)
 64 {
 65     if(!pListHead || !pTobeDeleted)
 66         return;
 67     
 68     //要删除的结点不是尾结点 
 69     if(pTobeDeleted->m_pNext != NULL)
 70     {
 71         ListNode* pNext = pTobeDeleted->m_pNext;
 72         pTobeDeleted->m_nValue = pNext->m_nValue;
 73         pTobeDeleted->m_pNext = pNext->m_pNext;
 74 
 75         delete pNext;
 76         pNext = NULL;
 77     }
 78     //链表只有一个结点，删除头结点(也是尾结点) 
 79     else if(*pListHead == pTobeDeleted)
 80     {
 81         delete pTobeDeleted;
 82         pTobeDeleted = NULL;
 83         *pListHead = NULL;
 84     }
 85     //链表中有多个结点，删除尾结点 ，只能遍历链表 
 86     else
 87     {
 88         ListNode* pNode = *pListHead;
 89         while(pNode->m_pNext != pTobeDeleted)
 90         {
 91             pNode = pNode->m_pNext;
 92         }
 93 
 94         pNode->m_pNext = NULL;
 95         delete pTobeDeleted;
 96         pTobeDeleted = NULL;
 97     }
 98 }
 99 
100 int  main()
101 {
102     //创建结点
103     ListNode* pNode1 = CreateListNode(1);
104     ListNode* pNode2 = CreateListNode(2);
105     ListNode* pNode3 = CreateListNode(3);
106     ListNode* pNode4 = CreateListNode(4);
107     ListNode* pNode5 = CreateListNode(5);
108     ListNode* pNode6 = CreateListNode(6);
109     ListNode* pNode7 = CreateListNode(7);
110     //连接结点 
111     ConnectListNode(pNode1,pNode2);
112     ConnectListNode(pNode2,pNode3);
113     ConnectListNode(pNode3,pNode4);
114     ConnectListNode(pNode4,pNode5);
115     ConnectListNode(pNode5,pNode6);
116     ConnectListNode(pNode6,pNode7);
117 
118     PrintList(pNode1);
119     //删除结点 
120     DeleteNode(&pNode1,pNode4);
121     //打印链表 
122     PrintList(pNode1);
123     //删除链表 
124     DestroyList(pNode1);
125     
126     return 0 ;
127 }