C++实现O(1)时间内删除链表结点

/*
 * 删除链表节点.cpp
 *
 *  Created on: 2018年4月13日
 *      Author: soyo
 */
#include<iostream>
using namespace std;
struct node
{
    int data;
    node * next;
};
node * create_head(node *p,int v)
{
    p=new node;
    p->data=v;
    p->next=NULL;
    return p;
}
node * add_list(node*head,int n)
{
    node *p,*p1;
    p=head;
    p1=new node;
    p1->data=n;
    p1->next=NULL;
    while(p->next!=NULL)
        p=p->next;
    p->next=p1;
    return head;
}
void println(node *head)
{
    if(head==NULL)
        return;
    while(head!=NULL)
    {
        cout<<head->data<<" ";
        head=head->next;
    }
    cout<<endl;
}
void deletNode(node**head,node*deleteNode)
{
    if(head==NULL||deleteNode==NULL)
        return;
   if(deleteNode->next!=NULL)   //要删除的结点不是尾结点
   {
       node *nextNode=deleteNode->next;
       deleteNode->data=nextNode->data;
       deleteNode->next=nextNode->next;
       delete nextNode;
       nextNode=NULL;
   }
   else if(*head==deleteNode)   //只有一个结点
   {
       delete deleteNode;
       deleteNode=NULL;
       *head=NULL;
   }
   else
   {
       node *p=*head;
       while(p->next!=deleteNode)    //删除的结点为尾结点
       {
           p=p->next;
       }
       p->next=NULL;
       delete deleteNode;
       deleteNode=NULL;
   }

}
int main()
{
   node *p,*head;
   int data=5;
   head=create_head(p,data);
   int a[]={2,4,6,7,8,9};
   int c=sizeof(a)/sizeof(int);
   for(int i=0;i<c;i++)
   {
       head=add_list(head,a[i]);
   }
   println(head);
   node *deNode=head;
     while(deNode->data!=7)
     {
         deNode=deNode->next;
     }
   node**Head;
   Head=&head;
   deletNode(Head,deNode);  //删除值为７的结点
   println(head);
   int a1=100;
   int *p1;
   p1=&a1;
   cout<<*p1<<endl;
   int **p2;
   p2=&p1;
   cout<<**p2<<endl;

}

结果：