1. 链表的概念及结构

1.1 链表的概念及结构

// 1、无头+单向+非循环链表增删查改实现
typedef int SLTDateType;
typedef struct SListNode
{
	SLTDateType data;
	struct SListNode* next;
}SListNode;

虽然有这么多的链表的结构，但是我们实际中最常用还是两种结构在这里插入图片描述

1.2 链表的实现(无头+单向+非循环链表增删查改实现)

// 1、无头+单向+非循环链表增删查改实现
typedef int SLTDateType;
typedef struct SListNode
{
	SLTDateType data;
	struct SListNode* next;
}SListNode;

1. 动态申请一个节点

// 动态申请一个节点
SListNode* BuySListNode(SLTDateType x)
{
	SListNode* node = (SListNode*)malloc(sizeof(SListNode));
	node->data = x;
	node->next = NULL;
 
	return node;
}

2. 单链表打印

void SListPrint(SListNode* plist)
{
	SListNode* cur = plist;
	while (cur)
	//while (cur != NULL)
	{
		printf("%d->", cur->data);
		cur = cur->next;
	}
	printf("NULL\n");
}

3. 单链表尾插

1. 找尾用 tail -> next

void SListPushBack(SListNode** pplist, SLTDateType x)
{
	SListNode* newnode = BuySListNode(x);
	if (*pplist == NULL)
	{
		*pplist = newnode;
	}
	else
	{
		SListNode* tail = *pplist;
		while (tail->next != NULL)
		{
			tail = tail->next;
		}
 
		tail->next = newnode;
	}
}

4. 单链表尾删 1、没有节点，一个节点 2、多个节点

void SListPopBack(SListNode** pplist)
{
	SListNode* prev = NULL;
	SListNode* tail = *pplist;
	// 1.空、只有一个节点
	// 2.两个及以上的节点
	if (tail == NULL || tail->next == NULL)
	{
		free(tail);
		*pplist = NULL;
	}
	else
	{
		while (tail->next)
		{
			prev = tail;
			tail = tail->next;
		}
 
		free(tail);
		tail = NULL;
 
		prev->next = NULL;
	}
}

5. 单链表头插

void SListPushFront(SListNode** pplist, SLTDateType x)
{
	assert(pplist);
 
	// 1.空
	// 2.非空
	SListNode* newnode = BuySListNode(x);
	if (*pplist == NULL)
	{
		*pplist = newnode;
	}
	else
	{
		newnode->next = *pplist;
		*pplist = newnode;
	}
}

6. 单链表头删 1、没有节点 2.一个节点 3、多个节点

先建立一个头节点，用于保留第二个结点的位置

void SListPopFront(SListNode** pplist)
{
	// 1.空
	// 2.一个
	// 3.两个及以上
	SListNode* first = *pplist;
	if (first == NULL)
	{
		return;
	}
	else if (first->next == NULL)
	{
		free(first);
		*pplist = NULL;
	}
	else
	{
		SListNode* next = first->next;
		free(first);
		*pplist = next;
	}
}

7. 单链表查找

SListNode* SListFind(SListNode* plist, SLTDateType x)
{
	SListNode* cur = plist;
	while (cur)
	{
		if (cur->data == x)
			return cur;
 
		cur = cur->next;
	}
 
	return NULL;
}

8. 单链表插入

可以利用7的查找后再插入

void SListInsertAfter(SLTNode* pos, SLTDataType x)
{
	assert(pos);

	SLTNode* newnode = BuySLTNode(x);
	newnode->next = pos->next;
	pos->next = newnode;
}

在pos之前插入需要遍历

void SListInsertBefore(SLTNode** pplist, SLTNode* pos, SLTDataType x)
{
	assert(pos);

	SLTNode* newnode = BuySLTNode(x);

	if (pos == *pplist) // 头插
	{
		newnode->next = pos;
		*pplist = newnode;
	}
	else
	{
		SLTNode* prev = NULL;
		SLTNode* cur = *pplist;
		while (cur != pos)
		{
			prev = cur;
			cur = cur->next;
		}

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

8. 删除pos之后的位置

void SListEraseAfter(SListNode* pos)
{
	assert(pos);
	// pos next nextnext
	SListNode* next = pos->next;
 
	if (next != NULL)
	{
		SListNode* nextnext = next->next;
		free(next);
		pos->next = nextnext;
	}
}