关于双向链表的增删改查和排序的C++实现

#include<iostream>

using namespace std;

class Node     //组成双向链表的节点
{
public:
  int data;
  Node * pNext;
  Node * pLast;
};

class List   //构造一个双向链表
{
private:
  Node * pHead;
  Node * pTail;
  int length;
public:
  List(int length)　　　　//创建双向链表
  {
    this->length=length;
    pHead=new Node();
    pHead->pLast=NULL;
    pTail=pHead;
    for(int i=0;i<length;i++)
    {
      Node * temp=new Node();
      cout<<"please enter the no"<<i+1<<" Node's data:";
      cin>>temp->data;
      temp->pNext=NULL;
      temp->pLast=pTail;
      pTail->pNext=temp;
      pTail=temp;
    }
  }
  
  void traverseList()　　　　//正向遍历
  {
    Node * p=pHead->pNext;
    while(p!=NULL)
    {
      cout<<p->data<<endl;
      p=p->pNext;
    }
  }
  
  void traverseListReturn()　　　　//逆向遍历
  {
    Node * p=pTail;
    while(p->pLast!=NULL)
    {
      cout<<p->data<<endl;
      p=p->pLast;
    }
  }
  
  void sortList()   //冒泡排序
  {
    Node * p=new Node();
    Node * q=new Node();
    int temp;
    for(p=pHead->pNext;p->pNext!=NULL;p=p->pNext)
    {
      for(q=p->pNext;q!=NULL;q=q->pNext)
      {
        if(q->data<p->data)
        {
          temp=q->data;
          q->data=p->data;
          p->data=temp;
        }
      }
    }
  }
  
  void sortListByInsertWay()    //插入排序
  {
    if(pHead->pNext==NULL||pHead->pNext->pNext==NULL)
    {
      return;
    }
    Node * p2=pHead->pNext->pNext;
    Node * p1=pHead;
    pHead->pNext->pNext=NULL;
    while(p2)
    {
      Node * pN=p2->pNext;
      while(p1->pNext)
      {
        if(p2->data<p1->pNext->data)
        {
          p2->pNext=p1->pNext;
          p2->pLast=p1;
          p1->pNext->pLast=p2;
          p1->pNext=p2;
          break;
        }
        p1=p1->pNext;
      }
      if(p1->pNext==NULL)
      {
        p2->pNext=NULL;
        p2->pLast=p1;
        p1->pNext=p2;
      }
      p2=pN;
    }
    
    //重新查找pTail的位置
    Node * pt=pHead;
    while(pt->pNext)
    {
      pt=pt->pNext;
    }
    pTail=pt;
  }
  
  void changeList(int num,int position)　　　　//修改链表中指定位置的节点
  {
    Node * p=pHead->pNext;
    if(position>length||position<=0)
    {
      cout<<"over stack !"<<endl;
      return;
    }
    for(int i=0;i<position-1;i++)
    {
      p=p->pNext;
    }
    p->data=num;
  }
  
  void insertList(int num,int position)　　　　//插入数据
  {
    Node * p=pHead->pNext;
    if(position>length||position<=0)
    {
      cout<<"over stack !"<<endl;
      return;
    }
    for(int i=0;i<position-1;i++)
    {
      p=p->pNext;
    }
    Node * temp=new Node();
    temp->data=num;
    temp->pNext=p;
    temp->pLast=p->pLast;
    p->pLast->pNext=temp;
    p->pLast=temp;
    length++;
  }
  
  void clearList()　　　　　　//清空
  {
    Node * q;
    Node * p=pHead->pNext;
    while(p!=NULL)
    {
      q=p;
      p=p->pNext;
      delete q;
    }
    p=NULL;
    q=NULL;
  }
  
  void deleteList(int position)　　　//删除指定位置的节点
  {
    Node * p=pHead->pNext;
    if(position>length||position<=0)
    {
      cout<<"over stack !"<<endl;
      return;
    }
    for(int i=0;i<position-1;i++)
    {
      p=p->pNext;
    }
    p->pLast->pNext=p->pNext;
    p->pNext->pLast=p->pLast;
    delete p;
    length--;
  }
  
  int getItemInList(int position)　　　　　　//查找指定位置的节点
  {
    Node * p=pHead->pNext;
    if(position>length||position<=0)
    {
      cout<<"over stack !"<<endl;
      return 0;
    }
    for(int i=0;i<position-1;i++)
    {
      p=p->pNext;
    }
    return p->data;
  }
  
  ~List()
  {
    Node * q;
    Node * p=pHead->pNext;
    while(p!=NULL)
    {
      q=p;
      p=p->pNext;
      delete q;
    }
    p=NULL;
    q=NULL;
  }
  
};

int main()
{
  List l(3);
  l.traverseList();
  cout<<"AFTER SORT------------------------------------------------------"<<endl;
//  l.sortList();       //冒泡排序
  l.sortListByInsertWay();  //插入排序
  l.traverseList();
  cout<<"AFTER INSERT-----------------------------------------------------"<<endl;
  l.insertList(55,1);
  l.traverseList();
  cout<<"AFTER DELETE-----------------------------------------------------"<<endl;
  l.deleteList(1);
  l.traverseList();
  cout<<"Return Traverse---------------------------------------------"<<endl;
  l.traverseListReturn();
  cout<<"Find the Second Node's data:"<<l.getItemInList(2)<<endl;
  return 0;
}