数据结构：循环链表

循环链表的概念：

循环链表是另一种形式的链式存贮结构。它的特点是表中最后一个结点的指针域指向头结点，整个链表形成一个环。

示意图：

代码实现：

clist.h

#pragma once
 
//循环链表
typedef struct CNode
{
	int data;
	struct CNode *next;
}CNode,*CList;
 
//循环链表初始化
void InitList(CList plist);
 
//头插
bool Insert_head(CList plist,int val);
 
//尾插
bool Insert_tail(CList plist,int val);
 
//查找
CNode *Search(CList plist,int key);
 
//删除
bool Delete(CList plist,int key);
 
//获取循环链表长度(数据结点的个数)
int GetLength(CList plist);
 
//判空
bool IsEmpty(CList plist);
 
//清空
void Clear(CList plist);
 
//摧毁
void Destroy(CList plist);
 
//打印循环链表
void Show(CList plist);

clist.cpp

#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
#include"clist.h"
 
//循环链表初始化
void InitList(CList plist)
{
  assert(plist != NULL);
  if(plist == NULL)
  {
     return ;
  }
  
  plist->next = plist;
}
 
//头插
bool Insert_head(CList plist,int val)
{
  assert(plist != NULL);
  if(assert == NULL)
  {
    return false;
  }
  
  CNode* p = (CNode*)malloc(sizeof(CNode));
  p->data = val;
  
  p->next = plist->next;
  plist->next = p;
  
  return true;
}
 
//尾插
bool Insert_tail(CList plist,int val)
{
  assert(plist != NULL);
  if(assert == NULL)
  {
    return false;
  }
  
  CNode* p = (CNode*)malloc(sizeof(CNode));
  p->data = val;
  
  NCode*q;
  //找尾巴
  for(q= plist; q->plist != plist; q= q->next)
    
  //将p插在q后面
  q->next = p;
  p->next = plist;
 
  return true;
}
 
//查找
CNode *Search(CList plist,int key)
{
  assert(plist != NULL);
	if(plist == NULL)
	{
		return false;
	}
 
	for(CNode *p = plist->next;p != plist;p = p->next)
	{
		if(p->data == key)
		{
			return p;
		}
	}
	return NULL;
}
 
//删除
bool Delete(CList plist,int key)
{
    assert(plist != NULL);
	if(plist == NULL)
	{
		return false;
	}
 
	CNode *p = SearchPri(plist,key);
	if(p == NULL)
	{
		return false;
	}
 
	CNode *q = p->next;
	p->next = q->next;
	free(q);
 
	return true;
}
 
//获取循环链表长度(数据结点的个数)
int GetLength(CList plist)
{
  int count = 0;
  for(CNode *p = plist->next;p != plist;p = p->next)//遍历所有结点
  {
     count++;
  }
  return count;
}
 
//判空
bool IsEmpty(CList plist)
{
  return plist->next = plist;
}
 
//清空
void Clear(CList plist)
{
  Destroy(plist);
}
 
//摧毁
void Destroy(CList plist)
{
  CNode*p;
  while(p->next != plist)
  {
   p = plist->next;
   plist->next = p->next;

   free(p);
  }
}
 
//打印循环链表
void Show(CList plist)
{
  CNode* p 
  for(p= plist->next;p !=plist;p = p->next )
  {
    printf("%d",p->data);
  }
  printf("\n");
}

主函数：

#include<stdio.h>
#include<vld.h>//测试内存是否泄露
#include"clist.h"
 
int main()
{
	CNode head1;
	CNode head2;
 
	//测试初始化
	InitList(&head1);
	InitList(&head2);
	for(int i = 0;i < 15;i++)
	{
		Insert_head(&head1,i);
		Insert_tail(&head2,i);
	}
	Show(&head1);
	Show(&head2);
 
	//测试删除
	Delete(&head2,6);
	Show(&head2);
 
	//测试获取单向循环链表的长度
	printf("%d\n",GetLength(&head1));
 
	//测试摧毁
	Destroy(&head1);
	Destroy(&head1);
	
 
	return 0;
}