循环链表

1.游标的定义 。定义一个当前指针。

2    获取当前游标指向的数据元素。

3   将游标重置指向链表中的第一个数据元素

 4  将游标移动指向到链表中的下一个数据元素。

5  直接指定删除链表中的某个数据元素。

#ifndef _CIRCLELIST_H_
#define _CIRCLELIST_H_

typedef void CircleList;

typedef struct _tag_CircleListNode CircleListNode;

struct _tag_CircleListNode
{
CircleListNode* next;
};

CircleList* CircleList_Create();

void CircleList_Destroy(CircleList* list);

void CircleList_Clear(CircleList* list);

int CircleList_Length(CircleList* list);

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

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

CircleListNode* 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);
#endif



#include "CircleList.h"
#include <malloc.h>
#include <stdio.h>

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

CircleList* CircleList_Create() //O(1)
{
TCircleList* ret = (TCircleList*)malloc(sizeof(TCircleList));

if(ret != NULL)
{
ret->length = 0;
ret->header.next = NULL;
ret->slider = NULL;
}
return ret;
}

void CircleList_Destroy(CircleList* list) //O(1)
{
free(list);
}

void CircleList_Clear(CircleList* list) //O(1)
{
TCircleList* sList = (TCircleList*)list;
if(sList != NULL)
{
sList->length = 0;
sList->header.next = NULL;
sList->slider = NULL;
}
}

int CircleList_Length(CircleList* list) //O(1)
{
TCircleList* sList = (TCircleList*)list;
int ret = -1;
if(sList != NULL)
{
ret = sList->length;
}
return ret;
}

int CircleList_Insert(CircleList* list,CircleListNode* node,int pos) //O(N)
{
TCircleList* sList = (TCircleList*)list;
int ret = (sList != NULL);
int i = 0;

ret = ret && (pos>=0) && (node != NULL);
if(ret)
{
CircleListNode* current = (CircleListNode*)sList;
CircleListNode* last =(CircleListNode* )CircleList_Get(sList,sList->length-1);

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

if((pos ==0) && (sList->length != 0))
{
last->next = node;
}

if(sList->length == 0)
{
sList->slider = node;
node->next = node;
}
sList->length++;
}

return ret;
}

CircleListNode* CircleList_Get(CircleList* list,int pos) //O(N)
{
TCircleList* sList = (TCircleList*)list;
CircleListNode* ret = NULL;
int i = 0;

if((sList != NULL) && (pos>=0))
{
CircleListNode* current = (CircleListNode*)sList;
for(i=0;i<pos;i++)
{
current = current->next;
}
ret = current->next;
}
return ret;
}

CircleListNode* CircleList_Delete(CircleList* list,int pos) //O(N)
{
TCircleList* sList = (TCircleList*)list;
CircleListNode* ret = NULL;
CircleListNode* first = sList->header.next;
CircleListNode* last = (CircleList_Get(sList,sList->length-1));
int i = 0;

if((sList != NULL) && (pos>=0))
{
CircleListNode* current = (CircleListNode*)sList;
for(i=0;i<pos;i++)
{
current = current->next;
}
ret = current->next;
current->next = ret->next;
sList->length--;

if(first == ret)
{
sList->header.next = ret->next;
last->next = ret->next;
}
if(sList->slider == ret)
{
sList->slider = ret->next;
}

if(sList->length == 0)
{
sList->header.next = NULL;
sList->slider = NULL;
}
}
return ret;
}

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

int i = 0;

if(sList != NULL)
{
CircleListNode* current = (CircleListNode*)sList;

for(i=0;i<sList->length;i++)
{
if(current->next == node)
{
ret = current->next;
break;
}
current = current->next;
}
if(ret != NULL)
{
CircleList_Delete(sList,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;
}

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;
}


#include <stdio.h>
#include <stdlib.h>
#include "CircleList.h"

/* run this program using the console pauser or add your own getch, system("pause") or input loop */

struct Value
{
CircleListNode header;
int v;
};

int main(int argc, char *argv[])
{
int i = 0;
CircleList* list = CircleList_Create();

struct Value v1;
struct Value v2;
struct Value v3;
struct Value v4;
struct Value v5;
struct Value v6;
struct Value v7;
struct Value 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*)&v1, 0);
CircleList_Insert(list, (CircleListNode*)&v2, 0);
CircleList_Insert(list, (CircleListNode*)&v3, 0);
CircleList_Insert(list, (CircleListNode*)&v4, 0);

CircleList_Insert(list, (CircleListNode*)&v5, 5);
// CircleList_Delete(list, 0);

for(i=0; i<2*CircleList_Length(list); i++)
{
struct Value* pv = (struct Value*)CircleList_Get(list, i);

printf("%d\n", pv->v);
}

printf("\n");

while( CircleList_Length(list) > 0 )
{
struct Value* pv = (struct Value*)CircleList_Delete(list, 0);

printf("%d\n", pv->v);
}

printf("\n");
/*
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));
*/
CircleList_Insert(list, (CircleListNode*)&v1, 0);
CircleList_Insert(list, (CircleListNode*)&v2, 0);
CircleList_Insert(list, (CircleListNode*)&v3, 0);
CircleList_Insert(list, (CircleListNode*)&v4, 0);
CircleList_Insert(list, (CircleListNode*)&v5, 0);
CircleList_Insert(list, (CircleListNode*)&v6, 0);
CircleList_Insert(list, (CircleListNode*)&v7, 0);
CircleList_Insert(list, (CircleListNode*)&v8, 0);

for(i=0; i<CircleList_Length(list); i++)
{
struct Value* pv = (struct Value*)CircleList_Next(list);

printf("%d\n", pv->v);
}

printf("\n");

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);

return 0;
}