1、基本概念
循环链表的定义：将单链表中最后一个数据元素的next指针指向第一个元素
循环链表拥有单链表的所有操作:
创建链表
销毁链表
获取链表长度
清空链表
获取第pos个元素操作
插入元素到位置pos
删除位置pos处的元素
游标的定义
在循环链表中可以定义一个“当前”指针，这个指针通常称为游标，可以通过这个游标来遍历链表中的所有元素。
循环链表新操作:
获取当前游标指向的数据元素
将游标重置指向链表中的第一个数据元素
将游标移动指向到链表中的下一个数据元素
直接指定删除链表中的某个数据元素
2、设计与实现
插入元素的分析
- 普通位置插入元素
- 添加第一个元素（第一次插入元素）
- 最后一个位置插入元素
- 第一个位置插入元素(如图):
添加第一个元素如图：
在最后一个位置插入元素如图：
删除节点
3、优点和缺点
优点：功能强了。循环链表只是在单链表的基础上做了一个加强，循环链表可以完全取代单链表的使用，循环链表的Next和Current操作可以高效的遍历链表中的所有元素
缺点：代码复杂度提高了
约瑟夫问题-循环链表典型应用
n 个人围成一个圆圈，首先第 1 个人从 1 开始一个人一个人顺时针报数，报到第 m 个人，令其出列。然后再从下一个人开始从 1 顺时针报数，报到第 m 个人，再令其出列，…，如此下去，求出列顺序。
CircleList.h
#ifndef _CIRCLELIST_H_
#define _CIRCLELIST_H_
typedef void CircleList;
/*
typedef struct _tag_CircleListNode CircleListNode;
struct _tag_CircleListNode
{
CircleListNode* next;
};
*/
typedef struct _tag_CircleListNode
{
struct _tag_CircleListNode * next;
}CircleListNode;
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);
//add
CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node);
CircleListNode* CircleList_Reset(CircleList* list);
CircleListNode* CircleList_Current(CircleList* list);
CircleListNode* CircleList_Next(CircleList* list);
#endif
CircleList.c
#include <stdio.h>
#include <malloc.h>
#include "CircleList.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)
{
return NULL;
}
ret->length = 0;
ret->header.next = NULL;
ret->slider = NULL;
return ret;
}
void CircleList_Destroy(CircleList* list) // O(1)
{
if (list == NULL)
{
return ;
}
free(list);
}
void CircleList_Clear(CircleList* list) // O(1)
{
TCircleList* sList = (TCircleList*)list;
if (sList == NULL)
{
return ;
}
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 (list == NULL)
{
return ret;
}
ret = sList->length;
return ret;
}
int CircleList_Insert(CircleList* list, CircleListNode* node, int pos) // O(n)
{
int ret = 0, i=0;
TCircleList* sList = (TCircleList*)list;
if (list == NULL || node== NULL || pos<0)
{
return -1;
}
//if( ret )
{
CircleListNode* current = (CircleListNode*)sList;
for(i=0; (i<pos) && (current->next != NULL); i++)
{
current = current->next;
}
//current->next 0号节点的地址
node->next = current->next; //1
current->next = node; //2
//若第一次插入节点
if( sList->length == 0 )
{
sList->slider = node;
}
sList->length++;
//若头插法
if( current == (CircleListNode*)sList )
{
//获取最后一个元素
CircleListNode* last = CircleList_Get(sList, sList->length - 1);
last->next = current->next; //3
}
}
return ret;
}
CircleListNode* CircleList_Get(CircleList* list, int pos) // O(n)
{
TCircleList* sList = (TCircleList*)list;
CircleListNode* ret = NULL;
int i = 0;
if (list==NULL || pos<0)
{
return NULL;
}
//if( (sList != NULL) && (pos >= 0) && (sList->length > 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;
int i = 0;
if( (sList != NULL) && (pos >= 0) && (sList->length > 0) )
{
CircleListNode* current = (CircleListNode*)sList;
CircleListNode* last = NULL;
for(i=0; i<pos; i++)
{
current = current->next;
}
//若删除第一个元素
if( current == (CircleListNode*)sList )
{
last = (CircleListNode*)CircleList_Get(sList, sList->length - 1);
}
//求要删除的元素
ret = current->next;
current->next = ret->next;
sList->length--;
//判断链表是否为空
if( last != NULL )
{
sList->header.next = ret->next;
last->next = ret->next;
}
//若删除的元素为游标所指的元素
if( sList->slider == ret )
{
sList->slider = ret->next;
}
//若删除元素后，链表长度为0
if( sList->length == 0 )
{
sList->header.next = NULL;
sList->slider = NULL;
}
}
return ret;
}
CircleListNode* CircleList_DeleteNode(CircleList* list, CircleListNode* node) // O(n)
{
TCircleList* sList = (TCircleList*)list;
CircleListNode* ret = NULL;
int i = 0;
if( sList != NULL )
{
CircleListNode* current = (CircleListNode*)sList;
//查找node在循环链表中的位置i
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(sList, i);
}
}
return ret;
}
CircleListNode* CircleList_Reset(CircleList* list) // O(1)
{
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) // O(1)
{
TCircleList* sList = (TCircleList*)list;
CircleListNode* ret = NULL;
if( sList != NULL )
{
ret = sList->slider;
}
return ret;
}
CircleListNode* CircleList_Next(CircleList* list) // O(1)
{
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"
struct Value
{
CircleListNode header;
int v;
};
void main()
{
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*)&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));
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);
system("pause");
return ;
}
时间： 2024-10-12 20:41:34