帶頭雙向循環鏈表的實現

無頭單向非循環鏈表的實現
常見的單鏈表面試題
DLinkList.h

#pragma once
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>

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

typedef struct List {
	struct ListNode *head;
}List;

void ListInit(List *plist);
void ListDestory(List *plist);
ListNode* BuyNode(DLDataType data);
void ListPrint(List *plist);

void ListPushBack(List *plist, DLDataType data);
void ListPopBack(List *plist);
void ListPushFront(List *plist, DLDataType data);
void ListPopFront(List *plist);

ListNode* ListFind(List *plist, DLDataType data);
void ListInsert(ListNode* pos, DLDataType data);//在指定位置前插入元素 
void ListErase(ListNode* pos);

DLinkList.c

#include"DLinkList.h"

void ListInit(List *plist)
{
	assert(plist);
	plist->head = BuyNode(0);
	plist->head->prev = plist->head;
	plist->head->next = plist->head;
}

ListNode* BuyNode(DLDataType data)
{
	ListNode* node = (ListNode*)malloc(sizeof(ListNode));
	node->data = data;
	node->prev = NULL;
	node->next = NULL;
	return node;
}

void ListDestory(List *plist)
{
	assert(plist);
	ListNode* cur = plist->head->next;
	while (cur != plist->head)
	{
		ListNode* next = cur->next;
		free(cur);
		cur = next;
	}
	
	free(plist->head);
	plist->head = NULL;
}

void ListPrint(List *plist)
{
	assert(plist);
	ListNode* cur = plist->head->next;
	while (cur != plist->head)
	{
		printf("%d <=> ", cur->data);
		cur = cur->next;
	}
	printf("NULL\n");
}

void ListPushBack(List *plist, DLDataType data)
{
	assert(plist);
	ListNode* node = BuyNode(data);
	ListNode* cur = plist->head;
	ListNode* tail = plist->head->prev;
	
	tail->next = node;
	node->next = cur;
	node->prev = tail;
	cur->prev = node;
}

void ListPopBack(List *plist)
{
	assert(plist);
	ListNode* cur = plist->head;
	ListNode* tail = cur->prev;
	ListNode* prev = tail->prev;

	cur->prev = prev;
	prev->next = cur;
	free(tail);
}

void ListPushFront(List* plist, DLDataType data)
{
	assert(plist);
	ListNode* cur = plist->head;
	ListNode* next = cur->next;
	ListNode* node = BuyNode(data);

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

void ListPopFront(List* plist)
{
	assert(plist);
	ListNode* prev = plist->head;
	ListNode* cur = prev->next;
	ListNode* next = cur->next;

	//鏈表中只有頭節點時，不做處理
	if (prev == cur)
		return;

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

ListNode* ListFind(List *plist, DLDataType data)
{
	assert(plist);
	ListNode* cur = plist->head->next;

	while (cur != plist->head)
	{
		if (cur->data == data)
			return cur;
		else
			cur = cur->next;
	}
	return NULL;
}

void ListInsert(ListNode* pos, DLDataType data)
{
	assert(pos);
	ListNode* prev = pos->prev;
	ListNode* node = BuyNode(data);
	
	prev->next = node;
	node->next = pos;
	node->prev = prev;
	pos->prev = node;
}

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

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