2024.2.4

 1.请用编程实现双向链表的头插、头删、尾插、尾删

源代码：

#include
#include
#include
typedef int datatype;
typedef struct Node//定义双向链表的节点结构体
{
	datatype data;//数据域
	struct Node *prev;//指针域 指向上个节点
	struct Node *next;//指针域 指向下个节点
}*doublelink;
doublelink create_node()
{
	doublelink s=(doublelink)malloc(sizeof(struct Node));
	if(NULL==s)
		return NULL;
	s->data=0;
	s->prev=NULL;
	s->next=NULL;
	return s;
}
doublelink insert_head(doublelink head,datatype element)
{
	doublelink s=create_node();
	if(NULL==s)
	{
		puts("create_node fail");
		return NULL;
	}
	s->data=element;
	if(head==NULL)
	{
		head=s;
		return head;
	}
	s->next=head;
	head->prev=head;
	head=s;
	return head;
}
doublelink insert_rear(doublelink head,datatype element)
{
	doublelink s=create_node();
	if(NULL==s)
	{
		puts("create_node fail");
		return NULL;
	}
	s->data=element;
	if(NULL==head)
	{
		head=s;
		return head;
	}
	doublelink p=head;
	while(p->next)
		p=p->next;
	p->next=s;
	s->prev=p;
	return head;
}
doublelink delete_head(doublelink head)
{
	if(head==NULL)
	{
		puts("empty");
		return NULL;
	}
	if(NULL==head->next)
	{
		free(head);
		return NULL;
	}
	doublelink del=head;
	head=head->next;
	head->prev=NULL;
	free(del);del=NULL;
	return head;
}
doublelink delete_rear(doublelink head)
{	
	if(head==NULL)
	{
		puts("empty");
		return NULL;
	}
	if(NULL==head->next)
	{
		free(head);
		return NULL;
	}
	doublelink p=head;
	while(p->next->next)
		p=p->next;
	doublelink del=p->next;
	p->next=NULL;
	free(del);del=NULL;
	return head;
}
int lengh(doublelink head)
{
	int l=0;
	while(head)
	{
		l++;
		head=head->next;
	}
	return l;
}
doublelink insert_index(doublelink head,int index,datatype element)
{
	int l=lengh(head);
	if(NULL==head || index<1 || index>l+1)
	{
		puts("empty or index error");
		return head;
	}
	if(1==index)
	{
		head=insert_head(head,element);
		return head;
	}
	if(l+1==index)
	{
		head=insert_rear(head,element);
		return head;
	}
	doublelink s=create_node();
	s->data=element;
	doublelink p=head;
	for(int i=1;inext;
	s->next=p->next;
	s->prev=p;
	p->next->prev=s;
	p->next=s;
	return head;
}
doublelink delete_index(doublelink head,int index)
{
	if(NULL==head || index<1 || index>lengh(head))
	{
		puts("empty or index error");
		return head;
	}
	if(1==index)
	{
		head=delete_head(head);
		return head;
	}
	if(index==lengh(head))
	{
		head=delete_rear(head);
		return head;
	}
	doublelink p=head;
	for(int i=1;inext;
	doublelink del=p->next;
	p->next=del->next;
	del->next->prev=p;
	free(del);del=NULL;
	return head;
}
void chg_index(doublelink head,int index,datatype element)
{	
	if(NULL==head || index<1 || index>lengh(head))
	{
		puts("empty or index error");
		return;
	}
	doublelink p=head;
	for(int i=1;inext;
	p->data=element;
}
void search_index(doublelink head,int index)
{	
	if(NULL==head || index<1 || index>lengh(head))
	{
		puts("empty or index error");
		return;
	}
	doublelink p=head;
	for(int i=1;inext;
	printf("search_index is: %d\n",p->data);
}
void output(doublelink head)
{
	while(head)
	{
		printf("%-4d",head->data);
		head=head->next;
	}
	puts("");
}
int main(int argc, const char *argv[])
{
	doublelink head=NULL;
	int len;
	printf("please enter the lengh of the doublelink:");
	scanf("%d",&len);
	datatype element;
	for(int i=0;i

 效果显示：

2.请用编程实现双向链表按任意位置插入、删除、修改、查找

//头文件
#ifndef __HEAD_H__
#define __HEAD_H__
#include
#include	
#include
typedef char datatype;
 
//定义双向链表结构体
typedef struct Node
{
	//数据域：存储数据元素
	datatype data;
	//指针域：下一个节点的地址
	struct Node *next;
	//指针域：上一个节点的地址
	struct Node *prev;
}*Doublelink;
 
Doublelink inert_head(Doublelink head,datatype element);
Doublelink creat();
void output(Doublelink head);
Doublelink inert_rear(Doublelink head,datatype element);
Doublelink det_head(Doublelink head);
Doublelink det_rear(Doublelink head);
int length(Doublelink head);
Doublelink inert_pos(Doublelink head,int pos,datatype element);
Doublelink det_pos(Doublelink head,int pos);
void find_pos(Doublelink head,int pos);
void cpy_pos(Doublelink head,int pos,datatype element);
#endif

//主函数
#include"head.h"
int main(int argc, const char *argv[])
{
	Doublelink head=NULL;
	datatype element;
	int n;
	printf("please enter n:");
	scanf("%d",&n);
	for(int i=0;i

//文本段
#include"head.h"
 
/*
 * function:    创建新节点
 * @param [ in] 
 * @param [out] 
 * @return      成功返回s 失败返回NULL
 */
Doublelink creat()
{
	Doublelink s=(Doublelink)malloc(sizeof(struct Node));
	if(s==NULL)
		return NULL;
	s->data=0;
	s->next=s->prev=NULL;
	return s;
}
/*
 * function:    头插
 * @param [ in] 
 * @param [out] head,element
 * @return      head
 */
Doublelink inert_head(Doublelink head,datatype element)
{
	Doublelink s=creat();
	s->data=element;
	if(NULL==head)
		head=s;
	else
	{
		s->next=head;
		head->prev=s;
		head=s;
	}
	return head;
}
/*
 * function:    遍历输出
 * @param [ in] 
 * @param [out] head
 * @return      head
 */
void output(Doublelink head)
{
	if(NULL==head)
	{
		puts("empty");
		return;
	}
	else
	{
		Doublelink p=head;
		while(p->next!=NULL)//p到倒数第二个节点
		{
			printf("%-5c",p->data);
			p=p->next;
		}
		printf("%-5c\n",p->data);//最后一个元素输出
	/*	while(p)//逆向输出
		{
			printf("%-5c",p->data);
			p=p->prev;
		}
		*/
	//	puts("");
		return;
	}
}
/*
 * function:    尾插
 * @param [ in] 
 * @param [out] head,element
 * @return      head
 */
Doublelink inert_rear(Doublelink head,datatype element)
{
	Doublelink s=creat();
	s->data=element;
	if(NULL==head)
		head=s;
	else
	{
		Doublelink p=head;
		while(p->next!=NULL)//找到最后一个节点
		{
	
			p=p->next;
		}
		p->next=s;
		s->prev=p;
	}
	return head;
}
/*
 * function:    头删
 * @param [ in] 
 * @param [out] head
 * @return      head
 */
Doublelink det_head(Doublelink head)
{
	if(NULL==head)
		return head;
	//多个节点>=1
	Doublelink p=head;
	head=p->next;
	head->prev=NULL;
	free(p);
	p=NULL;
	return head;
	
}
/*
 * function:    尾删
 * @param [ in] 
 * @param [out] head
 * @return      head
 */
Doublelink det_rear(Doublelink head)
{
	if(NULL==head)
		return head;
	else if(head->next==NULL)//一个节点
	{
		free(head);
		head=NULL;
		return head;
	}
	else//多个节点>=2
	{
		Doublelink p=head;
		while(p->next)
		p=p->next;
		p->prev->next=NULL;
		free(p);
		p=NULL;
		return head;
	}
}
/*
 * function:    计算链表长度
 * @param [ in] 
 * @param [out] head
 * @return      len
 */
int length(Doublelink head)
{
		int len=0;
		while(head)
	//	printf("%-5c\n",p->data);//最后一个元素输出		puts("");
		{
			len++;
			head=head->next;
		}
		return len;
}
	/*
	 * function:    任意位置插入
	 * @param [ in] 
	 * @param [out] head pos
	 * @return      head
	 */
Doublelink inert_pos(Doublelink head,int pos,datatype element)
	{
		int len=length(head);
		Doublelink s=creat();
		s->data=element;
		if(NULL==head||pos<1||pos>len+1)
		{
			puts("error");
			return NULL; 
		}
		if(pos==1)
		{
			head=inert_head(head,element);
			return head;
		}
		Doublelink p=head;
	for(int i=0;inext;
	}
	Doublelink k=p->prev;
	k->next=s;
	s->prev=k;
	s->next=p;
	p->prev=s;
	return head;
}
/*
 * function:    任意位置删除
 * @param [ in] 
 * @param [out] head pos
 * @return      head
 */
Doublelink det_pos(Doublelink head,int pos)
{
	int len=length(head);
	//printf("%d\n",len);
	if(NULL==head||pos<1||pos>len)
	{
		puts("error");
		return NULL;
	}
	if(pos==1)
	{
		head=det_head(head);
		return head;
	}
	else if(pos==len)
	{
		head=det_rear(head);
		return head;
	}
	Doublelink p=head;
	for(int i=0;inext;
	Doublelink k=p->prev;
	k->next=p->next;
	p->next->prev=k;
	free(p);
	p=NULL;
	return head;
}
/*
 * function:    逆置
 * @param [ in] 
 * @param [out] head
 * @return      head
 */
Doublelink rever(Doublelink head)
{
	if(NULL==head)
		return head;
	Doublelink p=head->next;
	head->next=NULL;
	p->prev=NULL;
	while(p)
	{
		Doublelink t=p;
		p=p->next;
		t->next=head;
		head->prev=t;
		t->prev=NULL;
		head=t;
	}
	return head;
}
void find_pos(Doublelink head,int pos)
{
	int len=length(head);
	if(NULL==head||pos<1||pos>len)
		return ;
	Doublelink p=head;
	for(int i=0;inext;
	printf("%c\n",p->data);
		
}
void cpy_pos(Doublelink head,int pos,datatype element)
{
	int len=length(head);
	if(NULL==head||pos<1||pos>len)
		return;
	Doublelink p=head;
	for(int i=0;inext;
	p->data=element;
}

3.请简述栈和队列的区别

答：栈是只允许栈顶插入和删除的操作受限的线性表（先进后出）；

       队列是只允许在队尾插入、队头删除的线性表（先进先出）；

4.请简述什么是内存泄露？

答：在释放空间时，指针位置并不在头部，指针之前的空间申请了内存空间，但没有释放，导致这部分内存无法再被其他程序使用。