循环链表的实现

circlelist.h文件

#pragma once
#include "stdio.h"
#include "stdlib.h"
#include "string.h"

typedef void CircleList;

typedef struct _tag_CircleListNode
{
	struct _tag_CircleListNode* next;
}CircleListNode;

typedef struct _tag_CircleList
{
	int length;
	CircleListNode header;
	CircleListNode* slider;
}TCircleList;

CircleList* CircleList_Create();

int CircleList_Destroy(CircleList* list);

int CircleList_Length(CircleList* list);

void CircleList_Clear(CircleList* list);

CircleListNode* CircleList_Get(CircleList* list,int pos);

CircleListNode* CircleList_Insert(CircleList* list, CircleListNode* node,int pos);

int CircleList_Delete(CircleList* list,int pos);

CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node);

CircleListNode* CircleList_Reset(CircleList* list);

CircleListNode* CircleList_Current(CircleList* list);

CircleListNode* CircleList_Next(CircleList* list);

circlelist.c文件

#include "circlelist.h"


CircleList* CircleList_Create()
{
	TCircleList* list = NULL;
	list = (TCircleList*)malloc(sizeof(TCircleList));
	memset(list, 0, sizeof(TCircleList));

	return list;
}

int CircleList_Destroy(CircleList* list)
{
	if (list != NULL)
	{
		free(list);
		list = NULL;
	}
	return 0;
}

int CircleList_Length(CircleList* list)
{
	TCircleList* rList = NULL;
	if (list == NULL)
	{
		printf("Length:list is NULL\n");
		return -1;
	}
	rList = (TCircleList*)list;

	return rList->length;
}

void CircleList_Clear(CircleList* list)
{
	TCircleList* rList = NULL;
	if (list == NULL)
	{
		printf("Clear:list is NULL\n");
		return ;
	}
	rList = (TCircleList*)list;
	rList->length = 0;
	rList->header.next = NULL;
	rList->slider = NULL;
	return ;
}

CircleListNode* CircleList_Get(CircleList* list,int pos)
{
	TCircleList* rList = NULL;
	CircleListNode* current = NULL;
	int i;
	if (list == NULL || pos < 0)
	{
		printf("Get:list is NULL or pos<0\n");
		return NULL;
	}
	rList = (TCircleList*)list;
	current = &(rList->header);

	for (i = 0;i < pos;i++)
	{
		current = current->next;
	}

	return current->next;
}

CircleListNode* CircleList_Insert(CircleList* list, CircleListNode* node, int pos)
{
	TCircleList* rList = NULL;
	CircleListNode* current = NULL;
	int i;
	if (list == NULL || node == NULL || pos < 0)
	{
		printf("Insert:list is NULL or pos<0\n");
		return NULL;
	}
	rList = (TCircleList*)list;
	current = &(rList->header);

	for (i = 0; (i < pos) && (current->next != NULL); i++)
	{
		current = current->next;
	}

	node->next = current->next;
	current->next = node;

	//若第一次插入节点
	if (rList->length == 0)
	{
		rList->slider = node;
	}

	rList->length++;

	//若为头插法
	if (current == &(rList->header))
	{
		//获取最后一个元素
		CircleListNode* last = CircleList_Get(list, rList->length - 1);
		last->next = current->next;
	}
	return node;
}

int CircleList_Delete(CircleList* list, int pos)
{
	TCircleList* rList = NULL;
	CircleListNode* current = NULL;
	CircleListNode* last = NULL;
	CircleListNode* node = NULL;
	int i = 0;
	if (list == NULL || pos < 0)
	{
		printf("Delete:list is NULL or pos<0\n");
		return -1;
	}
	rList = (TCircleList*)list;
	current = &(rList->header);

	if (pos >= 0 && rList->length > 0)
	{
		for (i = 0; i < pos; i++)
		{
			current = current->next;
		}

		//若删除第一个元素
		if (current == &(rList->header))
		{
			last = (CircleListNode*)CircleList_Get(rList, rList->length - 1);
		}

		//求要删除的元素
		node = current->next;
		current->next = node->next;

		rList->length--;
		//判断链表是否为空
		if (last != NULL)
		{
			rList->header.next = node->next;
			last->next = node->next;
		}

		//若删除的元素为游标所指的元素
		if (rList->slider == node)
		{
			rList->slider = node->next;
		}

		//若删除元素后链表长度为0
		if (rList->length == 0)
		{
			rList->header.next = NULL;
			rList->slider = NULL;
		}
	}

	return 0;
}

CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;
	int i = 0;

	if (sList != NULL)
	{
		CircleListNode* current = &(sList->header);

		//查找node在循环链表中的位置
		for (i=0;i<sList->length;i++)
		{
			if (current->next == node)
			{
				ret = current->next;
				break;
			}
			current = current->next;
		}

		//如果ret找到，根据i去删除
		if (ret != NULL)
		{
			CircleList_Delete(list, i);
		}
	}

	return ret;
}

CircleListNode* CircleList_Reset(CircleList* list)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;

	if (sList!=NULL)
	{
		sList->slider = sList->header.next;
		ret = sList->slider;
	}
	return ret;
}

CircleListNode* CircleList_Current(CircleList* list)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;

	if (sList != NULL)
	{
		ret = sList->slider;
	}
	return ret;
}

//把当前位置返回，并且游标下移
CircleListNode* CircleList_Next(CircleList* list)
{
	TCircleList* sList = (TCircleList*)list;
	CircleListNode* ret = NULL;

	if (sList != NULL && sList->slider != NULL)
	{
		ret = sList->slider;
		sList->slider = ret->next;
	}

	return ret;
}

main.c文件

#include "circlelist.h"

struct Value
{
	CircleListNode circlenode;
	int v;
};

int main()
{
	//约瑟夫问题求解
	int i = 0;
	CircleList* list = CircleList_Create();

	struct Value v1, v2, v3, v4, v5, v6, v7, v8;
	v1.v = 1;
	v2.v = 2;
	v3.v = 3;
	v4.v = 4;
	v5.v = 5;
	v6.v = 6;
	v7.v = 7;
	v8.v = 8;

	CircleList_Insert(list, (CircleListNode*)&v1, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v2, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v3, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v4, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v5, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v6, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v7, CircleList_Length(list));
	CircleList_Insert(list, (CircleListNode*)&v8, CircleList_Length(list));

	//怎样证明是循环链表
	for (i = 0; i < CircleList_Length(list); i++)
	{
		struct Value* pv = (struct Value*)CircleList_Get(list,i);
		printf("%d\n", pv->v);
	}

	printf("\n");

	for (i=0;i<CircleList_Length(list);i++)
	{
		struct Value* pv = (struct Value*)CircleList_Next(list);
		printf("%d\n", pv->v);
	}

	printf("\n");

	//重置游标
	CircleList_Reset(list);

	while (CircleList_Length(list)>0)
	{
		struct Value* pv= NULL;
		for (i=1;i<3;i++)
		{
			CircleList_Next(list);
		}
		pv = (struct Value*)CircleList_Current(list);
		printf("%d\n", pv->v);
		CircleList_DeleteNode(list, (CircleListNode*)pv);
	}

	CircleList_Destroy(list);

	system("pause");
	return 0;
}

关于循环链表概念，请看：https://www.cnblogs.com/zhaobinyouth/p/9826312.html