双链表的插入 删除

双链表其实 也没什么 只是多了一个前置链而已

双链表的定义

struct DNode
{
	int data;
	struct DNode *next;
	struct DNode *pre;
};

 

单链表的定义

struct DNode
{
	int data;
	struct DNode *next;
};

其他的可以看上一篇博客  大致相同

#ifndef HEAD_H
#define HEAD_H
#include <iostream>
using namespace std;
#include <cassert>
#include <cstdlib>
#include <cmath>
#include <sstream>
#include <fstream>
#include <string>
#include <algorithm>
#include <list>
#include <queue>
#include <vector>
#include <deque>
#include <stack>
#include <bitset>
#include <set>
#include <map>
#endif

struct DNode
{
	int data;
	struct DNode *next;
	struct DNode *pre;
};


DNode *Creat()
{
	DNode *head,*p,*s;
	head=(DNode *)malloc(sizeof(DNode));
	p=head;
	int temp;
	while (cin>>temp&&temp)
	{
		s=(DNode *)malloc(sizeof(DNode));
		s->data=temp;
		p->next=s;
		s->pre=p;
		p=s;
	}
	head=head->next;
	p->next=NULL;
	head->pre=NULL;
	return (head);
}

DNode *Insert(DNode *&head,int num)
{
	DNode *p,*s;
	s=(DNode *)malloc(sizeof(DNode));
	s->data=num;
	p=head;
	while (NULL!=p->next&&num>p->data)
	{
		p=p->next;
	}
	if (num<=p->data)
	{
		if (NULL==p->pre)
		{
			s->next=head;
			head->pre=s;
			head=s;
			head->pre=NULL;
		} 
		else
		{
			s->pre=p->pre;
			p->pre->next=s;
			s->next=p;
			p->pre=s;
		}
	} 
	else
	{
		p->next=s;
		s->pre=p;
		s->next=NULL;
	}
	return(head);
}

DNode *Del(DNode *&head,int num)
{
	DNode *p;
	p=head;
	while (NULL!=p->next&&num!=p->data)
	{
		p=p->next;
	}
	if (num==p->data)
	{
		if (NULL==p->pre)
		{
			head=p->next;
			p->next->pre=head;
			free(p);
		} 
		else if (NULL==p->next)
		{
			p->pre->next=NULL;
			free(p);
		}
		else
		{
			p->pre->next=p->next;
			p->next->pre=p->pre;
			free(p);
		}
	} 
	else
	{
		cout<<num<<" cound not be found"<<endl;
	}
	return head;
}

void Display(DNode *head)
{
	DNode *p;
	p=head;
	while (NULL!=p)
	{
		cout<<(p->data)<<" ";
		p=p->next;
	}
	cout<<endl;
}

 

#include "head.h"

int main()
{
	DNode *head;
	head=Creat();
	Display(head);
#ifndef DEBUG
	cout<<"please input an num to insert:";
#endif
	int insert_num;
	while (cin>>insert_num&&insert_num)
	{
		Insert(head,insert_num);
		Display(head);
	}
#ifndef DEBUG
cout<<"please input an number to delete:";
#endif
    int delete_num;
    while (cin>>delete_num&&delete_num)
    {
		Del(head,delete_num);
		Display(head);
    }
	return (EXIT_SUCCESS);
}