数据结构之链表---双向链表(一)

一、创建节点

LTNode* LTInit()
{
	LTNode* phead = CreateLTNode(-1);
	phead->next = phead;
	phead->prev = phead;
	return phead;
}

 

 二、初始化哨兵位

LTNode* CreateLTNode(LTDataType x)
{
	LTNode* newnode = (LTNode*)malloc(sizeof(LTNode));
	if (newnode == NULL)
	{
		perror("malloc fail");
		exit(-1);
	}

	newnode->val = x;
	newnode->next = NULL;
	newnode->prev = NULL;
	return newnode;
}

 

三、对链表进行尾插

void LTPushBack(LTNode* phead, LTDataType x)
{
	assert(phead);
	LTNode* tail = phead->prev;
	LTNode* newnode = CreateLTNode(x);

	tail->next = newnode;
	newnode->prev = tail;
	newnode->next = phead;
	phead->prev = newnode;
}

 

四、对链表进行尾删

void LTPopBack(LTNode* phead)
{
	assert(phead);
	LTNode* tail = phead->prev;
	LTNode* tailPrev = tail->prev;

	free(tail);
	tailPrev->next = phead;
	phead->prev = tailPrev;
}

 

五、对链表进行头插

void LTPushFront(LTNode* phead, LTDataType x)
{
	assert(phead);

	LTNode* newnode = CreateLTNode(x); 
	LTNode* first = phead->next;

	phead->next = newnode;
	newnode->prev = phead;
	newnode->next = first;
	first->prev = newnode;
}

 

 

六、对链表进行头删

void LTPopFront(LTNode* phead)
{
	assert(phead);
	assert(phead->next != phead);

	LTNode* first = phead->next;
	LTNode* second = first->next;

	phead->next = second;
	second->prev = phead;
	free(first);
	first = NULL;
}