数据结构之双向带头循环链表

最新推荐文章于 2026-01-10 20:50:22 发布

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#链表 #数据结构

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本文介绍双向带头循环链表的基本概念及其实现方法，包括链表的初始化、节点的插入与删除等常见操作。

文章目录

一、链表的概念

链表是一种物理存储结构上非连续、非顺序的存储结构，数据元素的逻辑顺序是通过链表中的指针链接次序实现的。

双向带头循环链表的结构

在这里插入图片描述

二、链表的实现

杂项

1.结构定义

typedef int LDataType;
typedef struct ListNode
{
	struct ListNode* next;
	struct ListNode* prev;
	int data;
}LT;

2.链表打印

void Print(LT* phead);

void Print(LT* phead)
{
	assert(phead);
	LT* cur = phead->next;
	printf("phead<=>");
	while (cur != phead)
	{
		printf("%d<=>", cur->data);
		cur = cur->next;
	}
	printf("phead\n");
}

3.申请空间

LT* BuyNode(int x);

LT* BuyNode(int x)
{
	LT* newnode = (LT*)malloc(sizeof(LT));
	if (newnode == NULL)
	{
		perror("malloc fail");
		exit(-1);
	}

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

1.链表初始化

LT* ListIint();

LT* ListIint()
{
	LT* guard = (LT*)malloc(sizeof(LT));
	if (guard == NULL)
	{
		perror("malloc fail");
		exit(-1);
	}

	guard->next = guard;
	guard->prev = guard;
	return guard;
}

2.尾插

在这里插入图片描述

void ListPushBack(LT* phead, int x);

void ListPushBack(LT* phead, int x)
{
	assert(phead);
	LT* node = BuyNode(x);

	LT* tail = phead->prev;
	tail->next = node;
	node->prev = tail;
	node->next = phead;
	phead->prev = node;
}

3.头插

在这里插入图片描述

void ListPushFront(LT* phead, int x);

void ListPushFront(LT* phead, int x)
{
	assert(phead);
	LT* next = phead->next;
	LT* node = BuyNode(x);

	node->next = next;
	node->prev = phead;
	phead->next = node;
	next->prev = node;
}

4.尾删

在这里插入图片描述

void ListPopBack(LT* phead);

void ListPopBack(LT* phead)
{
	assert(phead);
	assert(!ListEmpty(phead));
	LT* tail = phead->prev;
	phead->prev = tail->prev;
	tail->prev->next = phead;
	free(tail);
	tail = NULL;
}

5.头删

在这里插入图片描述

void ListPopFront(LT* phead);

void ListPopFront(LT* phead)
{
	assert(phead);
	assert(!ListEmpty(phead));
	LT* next = phead->next;
	phead->next = next->next;
	next->next->prev = phead;
	free(next);
	next = NULL;
}

6.链表长度

size_t ListSize(LT* phead);

size_t ListSize(LT* phead)
{
	assert(phead);
	int n = 0;
	LT* cur = phead->next;
	while (cur != phead)//遍历即可
	{
		n++;
		cur = cur->next;
	}
	return n;
}

7.数据查找

LT* ListFind(LT* phead, LDataType x);

LT* ListFind(LT* phead, LDataType x)
{
	assert(phead);
	LT* cur = phead->next;
	while (cur != phead)//遍历即可
	{
		if (cur->data == x)
			return cur;
		cur = cur->next;
	}
	return NULL;
}

8.pos位置插入

在这里插入图片描述

void ListInsert(LT* pos, LDataType x);

void ListInsert(LT* pos, LDataType x)
{
	assert(pos);
	LT* prev = pos->prev;
	LT* newnode = BuyNode(x);

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

9.pos位置删除

在这里插入图片描述

void ListErase(LT* pos);

void ListErase(LT* pos)
{
	assert(pos);
	LT* prev = pos->prev;

	prev->next = pos->next;
	pos->next->prev = prev;
	free(pos);
	pos = NULL;
}

10.判断链表是否为空

bool ListEmpty(LT* phead);

bool ListEmpty(LT* phead)
{
	assert(phead);
	return phead->next == phead;
}

11.销毁

void ListDestory(LT* phead);

void ListDestory(LT* phead)
{
	assert(phead);
	LT* cur = phead->next;
	while (cur != phead)
	{
		LT* next = cur->next;
		free(cur);
		cur = next;
	}

	free(phead);
	
}