手撕【双向链表】带头双向循环（2）

Test.c

DList.h

DList.c

SLInsert

SLErase

DList.c总代码

顺序表和链表的对比

今天继续再双向循环链表的基础上做修改。

❓提问：请你在10分钟内写一个带头双向循环链表。

其实我们只要把SLInsert 和 SLErase 写好就大功告成了！🆗

Test.c

#include"Dlist.h"
int main()
{
	SL* phead = SLInit();
	//头插
	SLPushFront(phead, 7);
	SLPushFront(phead, 77);
	SLPushFront(phead, 9);
	SLPushFront(phead, 99);
	SLPrint(phead);
	//头删
	SLPopFront(phead);
	SLPopFront(phead);
	SLPrint(phead);
	//尾插
	SLPushBack(phead,8);
	SLPushBack(phead, 88);
	SLPrint(phead);
	//尾删
	SLPopBack(phead);
	SLPopBack(phead);
	SLPrint(phead);
	//
	SLDestory(phead);
	phead = NULL;
	return 0;
}

DList.h

#pragma once
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>
typedef int SLDataType;
typedef struct SListNode
{
	SLDataType val;
	struct SListNode* prev;
	struct SListNode* next;
}SL;
//初始化
SL* SLInit();
//打印数据
SL* SLPrint(SL* phead);
//查询
SL* SLFind(SL* phead, SLDataType x);
//头插
void SLPushFront(SL* phead, SLDataType x);
//头删
void SLPopFront(SL* phead);
//尾插
void SLPushBack(SL* phead, SLDataType x);
//尾删
void SLPopBack(SL* phead);
//在pos的前面插入
void SLInsert(SL* pos, SLDataType x);
//删除pos位置
void SLErase(SL* pos);
//销毁
void SLDestory(SL* phead);

DList.c

SLInsert

//在pos的前面插入
void SLInsert(SL* pos, SLDataType x)
{
	assert(pos);
	SL* cur = pos->prev;
	SL* newnode = Createnewnode(x);
	newnode->next = pos;
	pos->prev = newnode;
	cur->next = newnode;
	newnode->prev = cur;
}

SLErase

//删除pos位置
void SLErase(SL* pos)
{
	assert(pos);
	SL* cur = pos->prev;
	SL* tail = pos->next;
	cur->next = tail;
	tail->prev = cur;
	free(pos);
	pos = NULL;
}

DList.c总代码

#include"Dlist.h"
//创建新的节点
SL* Createnewnode(SLDataType x)
{
	SL* newnode = (SL*)malloc(sizeof(SL));
	newnode->val = x;
	newnode->prev = NULL;
	newnode->next = NULL;
	return newnode;
}
//初始化
SL* SLInit()
{
	SL* phead = Createnewnode(-1);
	phead->prev = phead;
	phead->next = phead;
	return phead;
}
//打印
SL* SLPrint(SL* phead)
{
	assert(phead);
	assert(phead->next != phead);//不打印头节点
	SL* cur = phead->next;
	while (cur != phead)
	{
		printf("<=%d=>", cur->val);
		cur = cur->next;
	}
	printf("\n");
}
//查询
SL* SLFind(SL* phead, SLDataType x)
{
	assert(phead);
	SL* cur = phead->next;
	while (cur != phead)
	{
		if (cur->val == x)
		{
			return cur;
		}
	}
	return NULL;
}
//在pos的前面插入
void SLInsert(SL* pos, SLDataType x)
{
	assert(pos);
	SL* cur = pos->prev;
	SL* newnode = Createnewnode(x);
	newnode->next = pos;
	pos->prev = newnode;
	cur->next = newnode;
	newnode->prev = cur;
}
//删除pos位置
void SLErase(SL* pos)
{
	assert(pos);
	SL* cur = pos->prev;
	SL* tail = pos->next;
	cur->next = tail;
	tail->prev = cur;
	free(pos);
	pos = NULL;
}
//头插
void SLPushFront(SL* phead, SLDataType x)
{
	SLInsert(phead->next, x);
}
//头删
void SLPopFront(SL* phead)
{
	assert(phead->next != phead);//不删除头节点
	SLErase(phead->next);
}
//尾插
void SLPushBack(SL* phead, SLDataType x)
{
	SLInsert(phead, x);
}
//尾删
void SLPopBack(SL* phead)
{
	assert(phead->next != phead);//不删除头节点
	SLErase(phead->prev);
}
//销毁
void SLDestory(SL* phead)
{
	assert(phead);
	SL* cur = phead->next;
	while (cur != phead)
	{
		SL* tmp = cur->next;
		free(cur);
		cur = tmp;
	}
	free(phead);
	cur = NULL;
}