实现带头双向循环链表

带头双向循环链表

实现带头双向循环链表_第1张图片
描述:一个节点内包含两个指针,一个指向上一个节点,另一个指向下一个节点。哨兵位指向的下一个节点为头节点,哨兵位的上一个指向尾节点。
结构优势:高效率找尾节点;高效率插入与删除;无需判断多种复杂情况,如尾节点、空节点等。

实现带头双向循环链表

☀️list.h

#define _CRT_SECURE_NO_WARNINGS
#pragma once
#include
#include
#include

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

ListNode* BuyListNode(DataType x);
ListNode* InitList();
void DestroyList(ListNode* phead);

void Print(ListNode* phead);
int CountSize(ListNode* phead);

void PushBack1(ListNode* phead, DataType x);
void PushBack2(ListNode* phead, DataType x);

void PopBack1(ListNode* phead);
void PopBack2(ListNode* phead);

void PushFront1(ListNode* phead, DataType x);
void PushFront2(ListNode* phead, DataType x);

void PopFront1(ListNode* phead);
void PopFront2(ListNode* phead);

void Insert(ListNode* pos, DataType x);
void Erase(ListNode* pos);

☀️list.c

BuyListNode节点创建函数()

ListNode* BuyListNode(DataType x) {
	ListNode* node = (ListNode*)malloc(sizeof(ListNode));
	if (node == NULL) {
		perror("malloc fail");
		exit(-1);
	}
	node->data = x;
	node->prev = NULL;
	node->next = NULL;
	return node;
}

InitList链表初始化函数()

ListNode* InitList() {
	ListNode* phead = BuyListNode(0);
	phead->next = phead;
	phead->prev = phead;
	return phead;
}

DestroyList链表销毁函数()

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

打印节点信息函数Print()

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

统计节点个数函数CountSize()

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

在pos位置节点前插入函数Insert()

//在pos前插入
void Insert(ListNode* pos, DataType x) {
	assert(pos);
	ListNode* posprev = pos->prev;
	ListNode* newnode = BuyListNode(x);
	posprev->next = newnode;
	newnode->prev = posprev;
	newnode->next = pos;
	pos->prev = newnode;
}

删除pos位置节点函数Erase()

void Erase(ListNode* pos) {
	assert(pos);
	ListNode* posprev = pos->prev;
	ListNode* posnext = pos->next;
	free(pos);
	posprev->next = posnext;
	posnext->prev = posprev;
}

尾插(两种方法)PushBack1()&PushBack2()

void PushBack1(ListNode* phead, DataType x) {
	ListNode* tail = phead->prev;
	ListNode* newnode = BuyListNode(x);
	newnode->next = phead;
	phead->prev = newnode;
	tail->next = newnode;
	newnode->prev = tail;
}
void PushBack2(ListNode* phead, DataType x) {
	//尾插就相当于在哨兵位head前插入
	Insert(phead, x);
}

尾删(两种方法)PopBack1()&PopBack2()

void PopBack1(ListNode* phead) {
	assert(phead);
	assert(phead->next != phead);
	ListNode* tail = phead->prev;
	ListNode* tailprev = tail->prev;
	free(tail);
	tailprev->next = phead;
	phead->prev = tailprev;
}
void PopBack2(ListNode* phead) {
	//尾节点就是phead的prev节点
	Erase(phead->prev);
}

头插(两种方法)PushFront1()&PushFront2()

void PushFront1(ListNode* phead, DataType x) {
	assert(phead);
	ListNode* newnode = BuyListNode(x);
	ListNode* pheadnext = phead->next;
	newnode->next = pheadnext;
	pheadnext->prev = newnode;
	phead->next = newnode;
	newnode->prev = phead;
}
void PushFront2(ListNode* phead, DataType x) {
	//头插就相当于在phead后一个节点的前面插入
	assert(phead);
	Insert(phead->next, x);
}

头删(两种方法)PopFront1()&PopFront2()

void PopFront1(ListNode* phead) {
	assert(phead);
	assert(phead->next != phead);
	ListNode* first = phead->next;
	ListNode* second = first->next;
	free(first);
	phead->next = second;
	second->prev = phead;
}
void PopFront2(ListNode* phead) {
	//头节点时哨兵位phead的下一个节点
	Erase(phead->next);
}

☀️测试

测试尾插:test_PushBack(()

#define _CRT_SECURE_NO_WARNINGS
#include"list.h"
void test_PushBack() {
	ListNode* plist = InitList();
	PushBack1(plist, 1);
	PushBack1(plist, 2);
	PushBack1(plist, 3);
	PushBack2(plist, 1);
	PushBack2(plist, 2);
	PushBack2(plist, 3);
	Print(plist);
	DestroyList(plist);
}

测试结果:
在这里插入图片描述

测试尾删:test_PopBack()

void test_PopBack() {
	ListNode* plist = InitList();
	PushBack1(plist, 1);
	PushBack1(plist, 2);
	PushBack1(plist, 3);
	PushBack2(plist, 1);
	PushBack2(plist, 2);
	PushBack2(plist, 3);
	Print(plist);

	PopBack1(plist);
	Print(plist);
	PopBack2(plist);
	Print(plist);
	DestroyList(plist);
}

测试结果:
实现带头双向循环链表_第2张图片

测试头插:test_PushFront()

void test_PushFront() {
	ListNode* plist = InitList();
	PushFront1(plist, 1);
	PushFront1(plist, 2);
	PushFront1(plist, 3);
	PushFront2(plist, 1);
	PushFront2(plist, 2);
	PushFront2(plist, 3);
	Print(plist);
	DestroyList(plist);
}

测试结果:
在这里插入图片描述

测试头删:test_PopFront()

void test_PopFront() {
	ListNode* plist = InitList();
	PushFront1(plist, 1);
	PushFront1(plist, 2);
	PushFront1(plist, 3);
	PushFront2(plist, 1);
	PushFront2(plist, 2);
	PushFront2(plist, 3);
	Print(plist);

	PopFront1(plist);
	Print(plist);
	PopFront2(plist);
	Print(plist);
	DestroyList(plist);
}

测试结果:
实现带头双向循环链表_第3张图片

测试用主函数

int main() {
	//测试尾插
	test_PushBack();
	//测试尾删
	test_PopBack();
	//测试头插
	test_PushFront();
	//测试头删
	test_PopFront();
}

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