[数据结构与算法]【数据结构】双向链表-C语言版

带头结点的双向循环链表的实现

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038-List.h

#define  _CRT_SECURE_NO_WARNINGS  1

//带头结点

typedef int LTDataType;
typedef struct ListNode
{
	struct ListNode* prev;
	struct ListNode* next;
	LTDataType data;
}ListNode;

//创建新结点
ListNode* BuyListNode(LTDataType x);

//初始化
ListNode* ListInit();

//尾插
void ListPushBack(ListNode* phead, LTDataType x);

//头插
void ListPushFront(ListNode* phead, LTDataType x);

//尾删
void ListPopBack(ListNode* phead);

//头删
void ListPopFront(ListNode* phead);

//查找
ListNode* ListFind(ListNode* phead, LTDataType x);

//前一个位置插入
void ListInsert(ListNode* pos, LTDataType x);

//删除pos位
void ListErase(ListNode* pos);

//链表判空，空返回1，非空返回0
int ListEmpty(ListNode* phead);

//链表大小
int ListSize(ListNode* phead);

//链表销毁
void ListDestroy(ListNode* phead);

038-List.c

#define  _CRT_SECURE_NO_WARNINGS  1
#include "038-List.h"
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>

//带头结点

void ListPrint(ListNode* phead)
{
	ListNode* cur = phead->next;
	while (cur != phead)
	{
		printf("%d ", cur->data);
		cur = cur->next;
	}
	printf("\n");

}

//创建新结点
ListNode* BuyListNode(LTDataType x)
{
	ListNode* newNode = (ListNode*)malloc(sizeof(ListNode));
	newNode->prev = NULL;
	newNode->next = NULL;
	newNode->data = x;

	return newNode;
}

//初始化
ListNode* ListInit()
{
	ListNode* phead = BuyListNode(0);
	phead->prev = phead;
	phead->next = phead;

	return phead;
}

//尾插
void ListPushBack(ListNode* phead, LTDataType x)
{
	ListNode* tail = phead->prev;
	ListNode* newNode = BuyListNode(x);

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

//头插
void ListPushFront(ListNode* phead, LTDataType x)
{
	ListNode* first = phead->next;
	ListNode* newNode = BuyListNode(x);

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

//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;

}

//头删
//如果只有一个结点，那么就有问题
void ListPopFront(ListNode* phead)
{
	assert(phead);
	assert(phead->next != phead);

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

	free(first);

	phead->next = second;
	second->prev = phead;

}

//查找
ListNode* ListFind(ListNode* phead, LTDataType x)
{
	assert(phead);

	ListNode* cur = phead->next;
	while (cur != phead)
	{
		if (cur->data == x)
		{
			return cur;
		}
		cur = cur->next;
	}
	return NULL;
}

//在前一个位置插入
void ListInsert(ListNode* pos, LTDataType x)
{
	//assert(phead);
	ListNode* prev = pos->prev;
	ListNode* newNode = BuyListNode(x);

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

//删除pos位
void ListErase(ListNode* pos)
{
	ListNode* prev = pos->prev;
	ListNode* next = pos->next;

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

	free(pos);
}

//链表判空，空返回1，非空返回0
int ListEmpty(ListNode* phead)
{
	return phead->next == phead ? 1 : 0;//头结点的下一个是否指向头结点自己
}

//链表大小
int ListSize(ListNode* phead)
{
	assert(phead);

	int size = 0;
	ListNode* cur = phead->next;
	while (cur != phead)
	{
		size++;
		cur = cur->next;
	}
	return size;
}

//链表销毁
void ListDestroy(ListNode* phead)
{
	assert(phead);

	ListNode* cur = phead->next;
	while (cur != phead)
	{
		ListNode* next = cur->next;
		free(cur);
		cur = next;
	}

	free(phead);
}

038-test.c

#define  _CRT_SECURE_NO_WARNINGS  1
#include "038-List.h"
#include<stdio.h>
#include<assert.h>

//带头结点

testList1() {
	ListNode* plist = ListInit();
	ListPushBack(plist, 1);
	ListPrint(plist);
	
	ListPushBack(plist, 1);
	ListPrint(plist);

	ListPushFront(plist, 2);
	ListPrint(plist);

	ListPushBack(plist, 3);
	ListPrint(plist);

	ListPopBack(plist);
	ListPrint(plist);

	ListPopFront(plist);
	ListPrint(plist);

	

	ListPushFront(plist, 4);
	ListPrint(plist);

	ListPushFront(plist, 5);
	ListPrint(plist);

	ListNode* pos = ListFind(plist, 5);
	ListInsert(pos, 100);
	ListErase(pos);
	ListPrint(plist);
	
	printf("%d", ListSize(plist));

	ListDestroy(plist);
	plist = NULL;
}

int main()
{
	testList1();
	return 0;
}