剑指offer——链表

 #include"stdio.h"
 #include"stdlib.h"
 #include"iostream"
 using namespace std;

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

 ListNode* CreateListNode(int value)
 {
     ListNode* pNode=new ListNode();
     pNode->m_Value=value;
     pNode->m_pNext=nullptr;

     return pNode;
 }

 void ConnectListNodes(ListNode* pCurrent,ListNode* pNext)
 {
     if(pCurrent==nullptr)
     {
         cout<<"Error to connect two nodes."<<endl;
         exit();
     }
     pCurrent->m_pNext=pNext;
 }

 void PrintListNode(ListNode* pNode)
 {
     if(pNode==nullptr)
     {
         cout<<"The node is nullptr."<<endl;
     }
     else
     {
         cout<<"the value in node is: "<<pNode->m_Value<<endl;
     }
 }

 void PrintList(ListNode *pHead)
 {
     cout<<"PrintList starts."<<endl;

     ListNode* pNode=pHead;
     while(pNode!=nullptr)
     {
         cout<<pNode->m_Value<<" ";
         pNode=pNode->m_pNext;
     }
     cout<<endl<<"PrintList ends."<<endl;
 }

 void DestroyList(ListNode* pHead)
 {
     ListNode* pNode=pHead;
     while(pNode!=nullptr)
     {
         pHead=pHead->m_pNext;
         delete pNode;
         pNode=pHead;
     }
 }

 void AddToTail(ListNode** pHead,int value)
 {
     ListNode* pNode=CreateListNode(value);
     if(pHead==nullptr || *pHead==nullptr)
     {
         *pHead=pNode;
     }
     else
     {
         ListNode* pTemp=*pHead;
         while(pTemp->m_pNext!=nullptr)
             pTemp=pTemp->m_pNext;
         pTemp->m_pNext=pNode;
     }
 }

 void RemoveNode(ListNode** pHead,int value)
 {
     if(pHead == nullptr || *pHead == nullptr)
         return;

     ListNode* pToBeDeleted = nullptr;
     if((*pHead)->m_Value == value)
     {
         pToBeDeleted = *pHead;
         *pHead = (*pHead)->m_pNext;
     }
     else
     {
         ListNode* pNode = *pHead;
         while(pNode->m_pNext != nullptr && pNode->m_pNext->m_Value != value)
             pNode = pNode->m_pNext;

         if(pNode->m_pNext != nullptr && pNode->m_pNext->m_Value == value)
         {
             pToBeDeleted = pNode->m_pNext;
             pNode->m_pNext = pNode->m_pNext->m_pNext;
         }
     }

     if(pToBeDeleted != nullptr)
     {
         delete pToBeDeleted;
         pToBeDeleted = nullptr;//防止指正悬挂
     }
 }
 //O(1)复杂度
 void DeleteNode(ListNode** pHead,ListNode* pToBeDeleted)
 {
     if(*pHead==nullptr || pToBeDeleted==nullptr)
         return;
     if(pToBeDeleted->m_pNext!=nullptr)
     {
         ListNode* pNext=pToBeDeleted->m_pNext;
         pToBeDeleted->m_pNext=pNext->m_pNext;
         pToBeDeleted->m_Value=pNext->m_Value;
         delete pNext;
         pNext=nullptr;
     }
     else if(pToBeDeleted==*pHead)
     {
         delete pToBeDeleted;
         pToBeDeleted=nullptr;
         *pHead=nullptr;
     }
     else
     {
         ListNode* pNode=*pHead;
         while(pNode->m_pNext!=pToBeDeleted)
             pNode=pNode->m_pNext;
         pNode->m_pNext=nullptr;
         delete pToBeDeleted;
         pToBeDeleted=nullptr;
     }
 }

 ListNode* TheLastKthNode(ListNode* pHead,int k)
 {
     if(pHead==nullptr || k<=)
         return nullptr;
     ListNode* quickNode=pHead;
     ListNode* slowNode=pHead;
     int cnt=;
     while(quickNode->m_pNext!=nullptr&&cnt<k)
     {
         quickNode=quickNode->m_pNext;
         ++cnt;
     }
     if(cnt<k)
         return nullptr;
     while(quickNode->m_pNext!=nullptr)
     {
         quickNode=quickNode->m_pNext;
         slowNode=slowNode->m_pNext;
     }
     return slowNode;
 }

 ListNode* MeetingNode(ListNode* pHead)
 {
     if(pHead==nullptr)
         return nullptr;
     ListNode* quickNode=pHead;
     ListNode* slowNode=pHead;

     while(quickNode->m_pNext!=nullptr&&quickNode->m_pNext->m_pNext!=nullptr)
     {
         quickNode=quickNode->m_pNext->m_pNext;
         slowNode=slowNode->m_pNext;
         if(quickNode==slowNode)
             break;
     }
     if(quickNode!=slowNode)
     {
         return nullptr;
     }
     return slowNode;
 }

 ListNode* EntryNodeOfLoop(ListNode* pHead)
 {
     ListNode* meetingNode=MeetingNode(pHead);
     if(meetingNode==nullptr)
         return nullptr;
     int nodesInLoop=;
     ListNode* pTemp=meetingNode;
     while(pTemp->m_pNext!=meetingNode)
     {
         pTemp=pTemp->m_pNext;
         nodesInLoop++;
     }
     ListNode* quickNode=pHead;
     ListNode* slowNode=pHead;
     for(int i=;i<nodesInLoop;i++)
         quickNode=quickNode->m_pNext;
     while(slowNode!=quickNode)
     {
         quickNode=quickNode->m_pNext;
         slowNode=slowNode->m_pNext;
     }
     return slowNode;
 }