双向链表的C++实现 Implement of Doubly Linked List

最新推荐文章于 2022-08-27 12:06:53 发布

原创最新推荐文章于 2022-08-27 12:06:53 发布 · 1.5k 阅读

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本文介绍了一个双向链表的数据结构实现，包括头部插入、尾部插入、指定位置插入与删除等核心功能。提供了完整的C++代码示例，展示了如何构建、遍历、查找元素以及清空链表。

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实现了双向链表的以下功能

头部插入节点
尾部插入节点
n-th位置插入节点
n-th位置删除节点
清空
获取长度
查找某个值

判断是否为空

#include <iostream>
using namespace std;
struct DoublyLinkedList
{
	int val;
	DoublyLinkedList *pre;
	DoublyLinkedList *next;
};

void AddAtHead(DoublyLinkedList *&head, int data)
{
	DoublyLinkedList *node = new DoublyLinkedList;
	node->val = data;
	node->pre = NULL;
	node->next = NULL;

	if(head != NULL)
	{
		node->next = head;
		head->pre = node;
	}
	head = node;
}

//This function is different from the one in the implement of Linked List
//can add the node even though head is NULL by using *& instead of *
void AddAtTail(DoublyLinkedList *&head, int data)
{
	DoublyLinkedList *node = new DoublyLinkedList;
	node->val = data;
	node->pre = NULL;
	node->next = NULL;

	if (head == NULL)
	{
		head = node;
		return;
	}
	
	DoublyLinkedList *p = head; //must use another pointer as head is a reference
	while(p->next != NULL)//move the pointer to the last node
		p = p->next;

	p->next = node;
	node->pre = p;
}

void BuildDoublyLinkedList(DoublyLinkedList *&head,int a[], int n)
{
	//AddAtHead(head,a[0]);
	for (int i = 0; i < n; i++)
	{
		AddAtTail(head,a[i]);
	}
}

void Traverse(DoublyLinkedList *head)
{
	while (head!=NULL)
	{
		cout << head->val << " ";
		head = head->next;
	}
	cout << "\n";
}

int GetSize(DoublyLinkedList *head)
{
	int size = 0;
	while (head!=NULL)
	{
		head = head->next;
		size++;
	}
	return size;
}

bool IsEmpty(DoublyLinkedList *head)
{
	if(head == NULL) 
		return true;
	return false;
}

void MakeEmpty(DoublyLinkedList *&head)
{
	while(head!=NULL)
	{
		DoublyLinkedList *p = head;
		head = head->next;
		delete p;
		p = NULL;
	}
}

bool Find(DoublyLinkedList *head, int data)
{
	while (head != NULL)
	{
		if(head->val == data)
			return true;
		head = head->next;
	}
	return false;
}

void Insert(DoublyLinkedList *&head, int pos, int data)
{
	if(pos < 1) return;

	DoublyLinkedList *node = new DoublyLinkedList;
	node->val = data;
	node->pre = NULL;
	node->next = NULL;

	if (pos == 1)
	{
		node->next = head;
		if(head != NULL)
			head->pre = node;

		head = node;
		return;
	}

	DoublyLinkedList *p = head;
	int cnt = 0;
	while(cnt < pos-2 && p!=NULL)
	{
		p = p->next;
		cnt++;
	}

	if(p == NULL) return;

	node->pre = p;
	node->next = p->next;
	p->next = node;
}

void Remove(DoublyLinkedList *&head, int pos)
{
	if(pos < 1 || head == NULL) return;

	DoublyLinkedList *p = head;
	if(pos == 1)
	{
		head = p->next;
		head->pre = NULL;
		delete p;
		return;
	}

	int cnt = 0;
	while(cnt < pos-2 && p->next!=NULL)
	{
		p = p->next;
		cnt++;
	}

	if(p->next == NULL) return;

	DoublyLinkedList *tmp = p->next;
	p->next = p->next->next;
	p->next->next->pre = p;
	delete tmp;
}


int main(void)
{
	int a[] = {4,2,6,1,3,5,7};
	DoublyLinkedList *head = NULL;
	//Insert(head,1,10);
	Remove(head,1);
	BuildDoublyLinkedList(head,a,sizeof(a)/sizeof(a[0]));
	/*Traverse(head);
	AddAtHead(head,0);
	AddAtTail(head,8);
	Remove(head,1);*/
	Traverse(head);
	MakeEmpty(head);
	return 0;
}