循环链表的设计与基本操作的实现

一.循环链表的设计

二.循环链表的实现

三.循环链表的总结

一.循环链表的设计

1.循环链表的结构设计:

typedef struct CNode{

    int data;
    struct CNode* next;

}CNode ,*CList;

2.循环链表的示意图:

3.循环链表和单链表的区别:

唯一区别,没有空指针,尾节点的后继为头,为循环之意.

二.循环链表的实现

//初始化
void InitList(CList plist)
{
	assert(plist != NULL);
	if (plist == NULL)
		return;

	//头节点的数据域不使用
	plist->next = plist;//环形
}


//头插
bool Insert_head(CList plist, int val)
{
	assert(plist != NULL);
	if (plist == NULL)
		return false;

	//申请节点
	CNode* p = (CNode*)malloc(sizeof(CNode));
	assert(p != NULL);
	//放入数据
	p->data = val;
	//头插
	p->next = plist->next;
	plist->next = p;
	return true;

}

//尾插
bool Insert_tail(CList plist, int val)
{
	assert(plist != NULL);
	if (plist == NULL)
		return false;

	//创建新节点
	CNode* p = (CNode*)malloc(sizeof(CNode));
	assert(p != NULL);
	p->data = val;
	//找尾巴
	CNode* q;
	for (q = plist; q->next != plist; q = q->next)
	{
		;
	}
	//尾插
	p->next = q->next;//p->next=plist;
	q->next = p;

	return true;
}

//插入数据，在plist链表的pos位置插入val;
bool Insert(CList plist, int pos, int val)
{
	if (pos<0 || pos>GetLength(plist))
	{
		return false;
	}
	//申请节点
	CNode* p = (CNode*)malloc(sizeof(CNode));
	assert(p != NULL);
	p->data = val;
	//找位置
	CNode* q;
	int i = 0;
	for(q=plist;i<pos;i++,q=q->next)
	{
		;
	}
	//插入
	p->next = q->next;
	q->next = p;

	return true;
}

//判空
bool IsEmpty(CList plist)
{
	return plist->next == plist;
}

//获取数据节点的个数
int GetLength(CList plist)
{
	assert(plist != NULL);
	if (plist == NULL)
		return 0;
	int count = 0;
	for (CNode* p = plist->next; p != plist; p = p->next)
	{
		count++;
	}
	return count;
}

//在plist中查找第一个key值，找到返回节点地址，没有找到返回NULL；
CNode* Search(CList plist, int key)
{
	assert(plist != NULL);
	if (plist == NULL)
		return NULL;
	for (CNode* p = plist->next; p != plist; p = p->next)
	{
		if (p->data == key)
		{
			return p;
		}
	}
	return NULL;
}

//删除pos位置的值
bool DelPos(CList plist, int pos)
{
	if (pos < 0 || pos >= GetLength(plist))
	{
		return false;
	}
	CNode* p;
	int i;
	for (p = plist, i = 0; i < pos; i++, p = p->next)
	{
		;
	}
	CNode* q = p->next;//q是要删除的点

	p->next = q->next;
	free(q);

	return true;

}


bool DelVal(CList plist, int val)
{	
	CNode* p = GetPrio(plist, val);
	if (p == NULL)
	{
		return false;
	}
	CNode* q = p->next;//q为要删除的点
	p->next = q->next;
	free(q);

	return true;
}

//返回key的前驱地址，如果不存在返回NULL；
CNode* GetPrio(CList plist, int key)
{
	CNode* p;
	for (p = plist; p->next != plist; p = p->next)
	{
		if (p->next ->data == key)
		{

			return p;
		}
	}
	return NULL;

}

//返回key的后继地址，如果不存在返回NULL；
CNode* GetNext(CList plist, int key)
{
	CNode* p = Search(plist, key);
	if (p == NULL)
		return NULL;
	return p->next;
}

//输出
void Show(CList plist)
{
	for (CNode* p = plist->next; p != plist; p = p->next)
	{
		printf("%d  ", p->data);
	}
	printf("\n");
}

//清空数据
void Clear(CList plist)
{
	Destroy(plist);
}

//销毁整个内存
void Destroy(CList plist)
{
	//总是删除第一个数据节点
	CNode* p;
	while (plist->next != plist)
	{
		p = plist->next;
		plist->next = p->next;
		free(p);
	}
}