数据结构 带头结点的循环双向链表的基本操作

带头结点的循环双向链表

代码如下：

#include<assert.h>
#include<stdio.h>
#include<stdlib.h>

typedef int ElemType;

typedef union DataType
{
 int num; //用头结点的数据域存放结点个数
 ElemType value;
}DataType;
typedef struct CDLNode  //定义结点结构体
{
 DataType  data;
 struct CDLNode *prior;
 struct CDLNode *next;
}CDLNode,*CDLinkList;

void CDLinkList_Init(CDLinkList head)//初始化
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 
 head->next =head;
 head->prior =head;
 head->data.num =0;
}

static CDLinkList CDLinkList_FindPrior(CDLinkList head,int pos)  //找pos的前驱结点
{
 CDLinkList p=head;
 while(pos>0)
 {
  p=p->next ;
  pos--;
 }
 return p;
}

CDLinkList Apply_Node(ElemType val)  //申请新结点
{
 CDLinkList p=(CDLinkList)malloc(sizeof(CDLNode));
 assert (p!=NULL);
 if(p == NULL) return NULL;
 p->next =NULL;
 p->data.value =val;
 p ->prior =NULL;
 return p;
}

bool CDLinkList_Insert_Tail(CDLinkList head,ElemType val)  //尾插
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 CDLinkList p=Apply_Node(val);
 if(p==NULL) exit(0);
 
 p->prior =head->prior ;
 p->next =head;
 p->prior ->next =p;
 head->prior =p;
 head->data .num ++;
 return true;
}
 
bool CDLinkList_Insert_Pos(CDLinkList head,ElemType val,int pos)//按位置插入
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 if(pos<0||pos>head->data .num ) return false;

 if(pos==head->data .num)
 {
  CDLinkList_Insert_Tail(head,val);
 }
 else
 {
  CDLinkList s=Apply_Node(val);
  if(s==NULL) exit(0);

  CDLinkList p=CDLinkList_FindPrior(head,pos);//pos前驱
  if(p->next !=NULL)
  {
   p->next ->prior =s;
   s->next=p->next;
   p->next =s;
   s->prior =p;
   head->data .num ++;
  }
 }
 return true;
 }
 
bool CDLinkList_Insert_Head(CDLinkList head,ElemType val) //头插
{
 return CDLinkList_Insert_Pos (head,val,0);
}

bool CDLinkList_Delete_Tail(CDLinkList head)//尾删
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 
 CDLinkList p=head->prior ;
 p->prior->next =head;
 head->prior =p->prior ;
 free(p);
 head->data .num --;
 return true;
}

bool CDLinkList_Delete_Head(CDLinkList head)//头删
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 
 CDLinkList p=head->next ;
 head->next =p->next ;
 p->next ->prior =head;
 free(p);
 head->data .num --;
 return true;
}

bool CDLinkList_Delete_Pos(CDLinkList head,int pos)//按位置删
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 
 if(pos<0||pos>head->data .num -1) return false;
 
 if(pos==0)
 {
  CDLinkList_Delete_Head(head);
 }
 else if(pos==head->data .num -1)
 {
  CDLinkList_Delete_Tail (head);
 }
 else
 {
  CDLinkList p=CDLinkList_FindPrior(head,pos)->next ;//pos结点
  p->next->prior =p->prior;
  p->prior ->next =p->next ;
  free(p);
  head->data .num --;
 }
 return true;
}

int CDLinkList_Clear(CDLinkList head) //清除
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 
 while(head->data .num )
 {
  if(!CDLinkList_Delete_Tail(head))
  {
   return false;
  }
 }
 return true;
}

void Show(CDLinkList head) //输出链表
{
 assert(head!=NULL);
 if(head==NULL) exit(0);
 
 CDLinkList p=head->next ;
 while(p!=head)
 {
  printf("%d ",p->data .value );
  p=p->next ;
 }
 printf("\n");
}

int main()
{
 CDLNode head;
 CDLinkList_Init(&head);
 for(int i=1;i<8;i++)
 {
  CDLinkList_Insert_Tail(&head,i);//尾插
 }
 Show(&head);
 CDLinkList_Insert_Pos(&head,21,1);//按位置插
 Show(&head);
 CDLinkList_Insert_Head (&head,90);//头插
 Show(&head);
 CDLinkList_Delete_Tail(&head);//尾删
 Show(&head);
 CDLinkList_Delete_Head(&head);//头删
 Show(&head);
 CDLinkList_Delete_Pos(&head,3);//按位删
 Show(&head);
 CDLinkList_Clear(&head);//清除
 Show(&head);
 
 return 0;
}

运行结果如下：