数据结构--双链表(C语言)

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双链表：

双链表与单链表不同的是，其结构体中存在两个指针，“Next”指向直接后继，“Prior”指向直接前驱，链表的访问不再是单链表的单向访问(只能访问后继结点)，可以利用next和prior指针方便的进行双向访问(既可以访问后继结点也可以访问前驱结点)。

实现：

//结构体typedef struct node{    int data;    struct node *next;    struct node *prior;}Node;

#include "Link2.h"//初始化链表头结点//return:头结点地址Node *init_list(){Node *head;head = (Node *)malloc(sizeof(Node));if(!head){printf("Error!\n");exit(1);}head->data = 0;head->next = NULL;head->prior = NULL;//将头结点前驱结点置为NULLreturn head;}//队尾插入新结点//@num:新结点个数//@head:头结点void add_node(int num,Node *head){if(!head){//判断链表是否存在printf("The list is empty!\n");return ;}Node *p,*q;p = head;q = head;while(q->next)//循环q至链表队尾q=q->next;while(num--){p = (Node *)malloc(sizeof(Node));printf("input data to add:");scanf("%d",&p->data);p->next = NULL;//新结点的next指针为NULL(即将成为尾结点)p->prior = q;//新结点的前驱结点指向尾结点qq->next = p;//将p结点"挂"到q上，使p成为新的尾结点q = p;//q重新指向队尾}}//根据结点位置删除结点//@no:待删除结点位置//@head:头指针//return:成功返回删除结点的值，失败返回-1(默认没有结点的数据域为-1)int delete_node(int no,Node *head){if(!head){printf("The list is empty!\n");return -1;}Node *p,*q;int value;p = head;while(no-- && p->next){p = p->next;if(!p->next && no > 0){//当p为队尾且no还大于0时，链表长度不够printf("The length is less than \'no\'\n");return -1;}}q = p->prior;//q为p的前驱结点q->next = p->next;//q的next指针指向p的下一个节点,将p从链表中脱离if(p->next)//若p不是队尾结点，则将p下一结点的prior指针指向qp->next->prior = q;value = p->data;free(p);p = NULL;return value;}//根据结点位置修改结点的数据域//@no:待修改值的结点位置//@value:新值//@head:头结点//return:成功返回结点旧值，失败返回-1int change_node(int no,int value,Node *head){if(!head){printf("The list is empty!\n");return -1;}int oldvalue;Node *p = head;while(p->next && no--){p = p->next;if(!p->next && no > 0){printf("The list is less than no\n");return -1;}}oldvalue = p->data;p->data = value;return oldvalue;}//根据结点位置查找结点//@no:待查找结点位置//@head:头结点//return:成功返回结点值，失败返回-1int search_node(int no,Node *head){if(!head){printf("The list is empty!\n");return -1;}Node *p = head;while(p->next && no--){p = p->next;if(!p->next && no > 0){printf("The list is less than no!\n");return -1;}}return p->data;}//销毁链表//@head:头结点地址void destroy_list(Node **head){if(!*head){printf("The list is empty!\n");return ;}Node *p = *head;while(p->next){//循环删除head的下一个结点，直到只剩headp = p->next;(*head)->next = p->next;p->next = NULL;p->prior = NULL;free(p);p = *head;}free(p);//释放头结点p = NULL;*head = NULL;}//打印链表全部值//@head:头结点void print_list(Node *head){if(!head){printf("The list is empty!\n");return ;}Node *p = head;while(p->next){p = p->next;printf("%d\n",p->data);}}

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