【數據結構】線性錶鏈式存儲結構-循環鏈表

• 循環單鏈表將尾結點next指針域指向頭結點
• 循環雙鏈表將尾結點next指針指向頭結點，頭結點的prior指針指向尾結點
• 可通過p->next ==L來判斷尾結點，雙向鏈表可以通過L->prior來找到尾結點

循環鏈表應用實例

//宏定義
#define FAILED		1
#define SUCCESS		0

typedef struct CirSLinkNode
{
	int data;
	struct CirSLinkNode* next;
}CirSLinkNode;

typedef struct CirDLinkNode
{
	int data;
	struct CirDLinkNode* next;
	struct CirDLinkNode* prior;
}CirDLinkNode;

//帶頭結點的循環單鏈表，統計其data域值爲x的結點個數

int CountCirSLinkList(CirSLinkNode* L,int x)
{
	CirSLinkNode* p = L->next;
	int i = 0;
	while (p!=L)
	{
		if (p->data ==x)
			i++;
		p = p->next;
	}
	return i;
}

//刪除雙向循環鏈表中值爲x的第一個元素

int DelCirDLinkList(CirDLinkNode* L,int x)
{
	CirDLinkNode* p = L->next;
	while (p!=L &&p->data !=x)
		p = p->next;
	if (p == L)   FAILED;
	p->next->prior = p->prior;
	p->prior->next = p->next;
	free(p);
	return SUCCESS;
}

//判斷帶頭結點的雙向循環鏈表（帶有至少兩個結點）是否對稱
int SymCirDLinkList(CirDLinkNode* L)
{
	CirDLinkNode* h = L->next;
	CirDLinkNode* r = L->prior;
	int isSame = 1;
	while (isSame)
	{
		if (h->data != r->data)
			isSame = 0;
		else
		{
			if ((h->next == r->prior) || (h == r->prior)) break;
			h = h->next;
			r = r->prior;
		}
	}
	return  isSame;
}