双向链表的实现及头尾插入删除

一.双向链表的初始化

ListNode* LTInit()
{
	ListNode* Phead = ListCreate(-1);

	Phead->next = Phead;
	Phead->prev = Phead;

	return Phead;
}

二.创建返回链表的头结点

ListNode* ListCreate(LTDataType x)
{
	ListNode* newnode = (ListNode*)malloc(sizeof(ListNode));

	if (newnode == NULL)
	{
		perror("malloc fial");
		exit(-1);
	}
	newnode->data = x;
	newnode->next = NULL;
	newnode->prev = NULL;
}

三.双向链表销毁

void ListDestory(ListNode* pHead)
{
	assert(pHead);

	ListNode* cur = pHead->next;
	while (cur != NULL)
	{
		ListNode* next = cur->next;
		free(cur);
		cur = next;
	}
	free(pHead);
	//pHead = NULL;
}

四. 双向链表打印

void ListPrint(ListNode* pHead)
{
	assert(pHead);
	printf("哨兵位");

	ListNode* cur = pHead->next;

	while (cur != pHead)
	{
		printf("%d >> ", cur->data);
		cur = cur->next;
	}
	printf("\n");
}

五.双向链表尾插

void ListPushBack(ListNode* pHead, LTDataType x)
{
	ListNode* tail = pHead->prev;

	ListNode* newnode = ListCreate(x);
	newnode->prev = tail;
	newnode->next = pHead;
	pHead->prev = newnode;

	tail->next = newnode;

}

六. 双向链表尾删

void ListPopBack(ListNode* pHead)
{
	assert(pHead);
	assert(pHead->next != pHead);

	//ListNode* tail = pHead->prev;
	//ListNode* tailprev = tail->prev;

	//free(tail);

	//tailprev->next = pHead;
	//pHead->prev = tailprev;


	ListErase(pHead->prev);
}

七. 双向链表头插

void ListPushFront(ListNode* pHead, LTDataType x)
{
	assert(pHead);

	ListNode* newnode = ListCreate(x);

	newnode->next = pHead->next;
	pHead->next->prev = newnode;

	newnode->prev = pHead;
	pHead->next = newnode;
}

八.双向链表头删

void ListPopFront(ListNode* pHead)
{
	assert(pHead);
	assert(pHead->next != pHead);

	//ListNode* first = pHead->next;
	//ListNode* second = first->next;

	//pHead->next = second;
	//second->prev = pHead;
	//free(first);
	//first = NULL;

	ListErase(pHead->next);

}

九.双向链表的查找

ListNode* ListFind(ListNode* pHead, LTDataType x)
{
	ListNode* cur = pHead->next;
	while (cur != pHead)
	{
		if (cur->data == x)
		{
			return cur;
		}
		cur = cur->next;
	}
	return NULL;
}

十.双向链表在pos的前面进行插入

void ListInsert(ListNode* pos, LTDataType x)
{
	assert(pos);
	ListNode* posPrev = pos->prev;
	ListNode* newnode = ListCreate(x);
	posPrev->next = newnode;
	newnode->prev = posPrev;
	newnode->next = pos;
	pos->prev = newnode;
}

十一. 双向链表删除pos位置的节点

void ListErase(ListNode* pos)
{
	assert(pos);

	ListNode* posNext = pos->next;
	ListNode* posprev = pos->prev;

	posprev->next = posNext;
	posNext->prev = posprev;

	free(pos);
	pos = NULL;

}