数据结构学习——双向链表

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前言——双向链表含义

双向链表也叫双链表，是链表的一种，它的每个数据结点中都有两个指针，分别指向直接后继和直接前驱。所以，从双向链表中的任意一个结点开始，都可以很方便地访问它的前驱结点和后继结点。一般我们都构造双向循环链表。

一、双向链表结构（图解）

二、 双向链表的实际操作

1、 结构

/**
 * Double linked list of integers. The key is char.
 */
typedef struct DoubleLinkedNode
{
	char data;
	struct DoubleLinkedNode *previous;
	struct DoubleLinkedNode *next;
}DLNode,*DLNodePtr;

2、创建头结点

/**
 * Initialize the list with a header.
 * @return The pointer to the header.
 */
DLNodePtr initLinkList(){
 
    DLNodePtr tempHeader =(DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
    tempHeader->data = '\0';
    tempHeader->previous = NULL;
    tempHeader->next=NULL;
    return tempHeader;
}

3、打印

/**
 * Print the list.
 * @param paraHeader The header of the list.
 */
void printList(DLNodePtr paraHeader)
{
	DLNodePtr p= paraHeader->next;
	while(p!=NULL)
	{
		printf("%c",p->data);
		p = p->next;
	}
	printf("\r\n");
}

4、插入

void insertElement(DLNodePtr paraHeader,char paraChar,int paraPosition)
{
	DLNodePtr p,q,r;
	p = paraHeader;
	int i;
	for (i=0;i< paraPosition;i++)
	{
		p=p->next;
		if(p==NULL)
		{
			printf("The position %d is beyond the scope of the list.",paraPosition);
			return;
		}
	}
	
	q=(DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
	q->data = paraChar;
	
	r = p->next;
	q->next = p->next;
	q->previous = p;
	p->next = q;
	if(r!=NULL)
	{
		r->previous = q;
	}
}

5、定位

void locateELement(DLNodePtr paraHeader,char paraChar)
{
	DLNodePtr p,q,r;
	int i=1;
	p=paraHeader;
	while((p->next !=NULL)&&(p->next->data !=paraChar))
	{
		p=p->next;
		i++;
	}
	if(p->next == NULL)
	{
		printf("The char '%c' does not exist.\r\n",paraChar);
		return;
	}
	printf("%d\n",i);
}

6、删除

void deleteElement(DLNodePtr paraHeader,char paraChar)
{
	DLNodePtr p,q,r;
	p=paraHeader;
	
	while((p->next !=NULL)&&(p->next->data !=paraChar))
	{
		p=p->next;
	}
	
	if(p->next == NULL)
	{
		printf("The char '%c' does not exist.\r\n",paraChar);
		return;
	}
	
	q=p->next;
	r=q->next;
	p->next=r;
	if(r!=NULL)
	{
		r->previous = p;
	}
	
	free(q);
}

完整代码

#include 
#include 
#include  
typedef struct DoubleLinkedNode
{
	char data;
	struct DoubleLinkedNode *previous;
	struct DoubleLinkedNode *next;
}DLNode,*DLNodePtr;
 
DLNodePtr initLinkList(){
 
    DLNodePtr tempHeader =(DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
    tempHeader->data = '\0';
    tempHeader->previous = NULL;
    tempHeader->next=NULL;
    return tempHeader;
}
 
void printList(DLNodePtr paraHeader)
{
	DLNodePtr p= paraHeader->next;
	while(p!=NULL)
	{
		printf("%c",p->data);
		p = p->next;
	}
	printf("\r\n");
}
 
void insertElement(DLNodePtr paraHeader,char paraChar,int paraPosition)
{
	DLNodePtr p,q,r;
	p = paraHeader;
	int i;
	for (i=0;i< paraPosition;i++)
	{
		p=p->next;
		if(p==NULL)
		{
			printf("The position %d is beyond the scope of the list.",paraPosition);
			return;
		}
	}
	
	q=(DLNodePtr)malloc(sizeof(struct DoubleLinkedNode));
	q->data = paraChar;
	
	r = p->next;
	q->next = p->next;
	q->previous = p;
	p->next = q;
	if(r!=NULL)
	{
		r->previous = q;
	}
}

void locateELement(DLNodePtr paraHeader,char paraChar)
{
	DLNodePtr p,q,r;
	int i=1;
	p=paraHeader;
	while((p->next !=NULL)&&(p->next->data !=paraChar))
	{
		p=p->next;
		i++;
	}
	if(p->next == NULL)
	{
		printf("The char '%c' does not exist.\r\n",paraChar);
		return;
	}
	printf("%d\n",i);
}
 
void deleteElement(DLNodePtr paraHeader,char paraChar)
{
	DLNodePtr p,q,r;
	p=paraHeader;
	
	while((p->next !=NULL)&&(p->next->data !=paraChar))
	{
		p=p->next;
	}
	
	if(p->next == NULL)
	{
		printf("The char '%c' does not exist.\r\n",paraChar);
		return;
	}
	
	q=p->next;
	r=q->next;
	p->next=r;
	if(r!=NULL)
	{
		r->previous = p;
	}
	
	free(q);
}
 
 

 
void insertDeleteTest()
{
	DLNodePtr tempList = initLinkList();
	printList(tempList);
	
	insertElement(tempList,'p',0);
	insertElement(tempList,'o',1);
	insertElement(tempList,'l',2);
	insertElement(tempList,'l',3);
	insertElement(tempList,'e',4);
	insertElement(tempList,'n',5);
	printList(tempList) ;
	locateELement(tempList,'l');
	
	
	deleteElement(tempList,'o');
	deleteElement(tempList,'e');
	printList(tempList);
	
}
 
 
void basicAddressTest(){
	DLNode tempNode1,tempNode2;
	tempNode1.data = 4;
	tempNode1.next = NULL;
	tempNode2.data = 6;
	tempNode2.next = NULL;
	printf("The first node: %d,%d,%d\r\n",
	&tempNode1,&tempNode1.data,&tempNode1.next);
	printf("The Second node: %d,%d,%d\r\n",
	&tempNode2,&tempNode2.data,&tempNode2.next);
 
	tempNode1.next = &tempNode2;
	
}
 
int main()
{
	insertDeleteTest();
	basicAddressTest();
}
 
 
 
 
 

运行结果