循环链表的插入和删除

循环链表可以用来使计算机处理内存工作区或输出至数据缓冲区。

循环链表的插入和删除

   
     

    
      
    
      #include
    
      "
    
      iostream
    
      "
    
      
#include
    
      "
    
      stdlib.h
    
      "
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      struct
    
       clist
{
 
    
      int
    
       data;
 
    
      struct
    
       clist 
    
      *
    
      next;
};
typedef 
    
      struct
    
       clist cnode;
typedef cnode 
    
      *
    
      clink;


    
      /*
    
      -----循环链表的输出------
    
      */
    
      


    
      void
    
       printclist( clink head)
{
 clink ptr;
 head
    
      =
    
      head
    
      ->
    
      next;
 ptr
    
      =
    
      head;
 
    
      do
    
      
 {
 printf(
    
      "
    
      [%d]
    
      "
    
      ,ptr
    
      ->
    
      data);
 ptr
    
      =
    
      ptr
    
      ->
    
      next; 
 }
    
      while
    
      (head
    
      !=
    
      ptr 
    
      &&
    
       head 
    
      !=
    
      head
    
      ->
    
      next);
 printf(
    
      "
    
      \n
    
      "
    
      );

}

    
      /*
    
      -----循环链表的结点插入----
    
      */
    
      

clink insertnode(clink head,clink ptr,
    
      int
    
       value)
{
 clink new_node;
 new_node
    
      =
    
      (clink) malloc(
    
      sizeof
    
      (cnode));
 
    
      if
    
      (
    
      !
    
      new_node)
 
    
      return
    
       NULL;
 new_node
    
      ->
    
      data
    
      =
    
      value;
 new_node
    
      ->
    
      next
    
      =
    
      NULL;

 
    
      if
    
      (head
    
      ==
    
      NULL)
 {
 new_node
    
      ->
    
      next
    
      =
    
      new_node;
 
    
      return
    
       new_node;
 }
 
    
      if
    
      (ptr
    
      ==
    
      NULL)
 {
 
    
      /*
    
      ----情况1：插在第一结点之前---
    
      */
    
      
 new_node
    
      ->
    
      next
    
      =
    
      head
    
      ->
    
      next;
 head
    
      ->
    
      next
    
      ->
    
      next
    
      =
    
      new_node;
 }
 
    
      else
    
       
 {
 
    
      /*
    
      -----情况2：插在结点之后-------
    
      */
    
      
 new_node
    
      ->
    
      next
    
      =
    
      ptr
    
      ->
    
      next;
 ptr
    
      ->
    
      next
    
      =
    
      new_node;
 }
 
    
      if
    
      (ptr
    
      ==
    
      head)
 head
    
      =
    
      new_node;
 
    
      return
    
       head;
}

    
      /*
    
      ---循环链表结点删除---
    
      */
    
      
clink deletenode(clink head,clink ptr)
{
 clink previous;
 
    
      if
    
      (head
    
      ==
    
      NULL)
 {
 
    
      /*
    
      ----情况1：删除第一个结点----
    
      */
    
      
 head
    
      ->
    
      next
    
      =
    
      ptr
    
      ->
    
      next;
 }
 
    
      else
    
      
 {
 
    
      /*
    
      --情况2：删除中间结点---
    
      */
    
      
 previous
    
      =
    
      head;
 
    
      if
    
      (head
    
      !=
    
      head
    
      ->
    
      next)
 
    
      while
    
      (previous
    
      ->
    
      next
    
      !=
    
      ptr)
 previous
    
      =
    
      previous
    
      ->
    
      next;
 previous
    
      ->
    
      next
    
      =
    
      ptr
    
      ->
    
      next;
 }
 
    
      if
    
      (ptr
    
      ==
    
      head)
 head
    
      =
    
      previous;
 free(ptr);
 
    
      return
    
       head;
}


    
      /*
    
      使用插入结点的方式来创建链表，完成后将链表内容输出，然后删除前后两结点
    
      */
    
      


    
      int
    
       main()
{
 clink head
    
      =
    
      NULL;
 
    
      int
    
       list[
    
      6
    
      ]
    
      =
    
      {
    
      9
    
      ,
    
      7
    
      ,
    
      3
    
      ,
    
      4
    
      ,
    
      5
    
      ,
    
      6
    
      };
 
    
      int
    
       i;

 head
    
      =
    
      insertnode(head,head,list[
    
      0
    
      ]);
 printf(
    
      "
    
      创建第一个结点： 
    
      "
    
      );
 printclist(head);
 
    
      /*
    
      ---情况1：插在第一结点前----
    
      */
    
      
 head
    
      =
    
      insertnode(head,NULL,list[
    
      1
    
      ]);
 printf(
    
      "
    
      插入第一结点之前： 
    
      "
    
      );
 printclist(head);
 
    
      for
    
      (i
    
      =
    
      2
    
      ;i
    
      <
    
      6
    
      ;i
    
      ++
    
      )
 {
 
    
      /*
    
      ---情况2:插在结点之后-----
    
      */
    
      
 head
    
      =
    
      insertnode(head,head
    
      ->
    
      next,list[i]);
 printf(
    
      "
    
      插入结点之后： 
    
      "
    
      );
 printclist(head);
 }
 
    
      /*
    
      ---情况1：删除第一个结点---
    
      */
    
      
 head
    
      =
    
      deletenode(head,head
    
      ->
    
      next);
 printf(
    
      "
    
      删除第一个结点： 
    
      "
    
      );
 printclist(head);
 
    
      /*
    
      --删除最后一个结点--
    
      */
    
      
 printf(
    
      "
    
      删除最后一个结点： 
    
      "
    
      );
 head
    
      =
    
      deletenode(head,head);
 printclist(head);
}