问：在双向链表的开头插入新节点的程序。

2025年3月17日 | 阅读 8 分钟

说明

在此程序中，我们将创建一个双向链表，并将每个新节点插入到列表的开头。如果列表为空，则 head 和 tail 都将指向新添加的节点。如果列表不为空，则将新节点插入到列表的开头，使得 head 的前驱指向新节点。将新节点设为列表的 head，其前驱指向 null。

Program to insert a new node at the beginning of the doubly linked list

考虑上面的例子。最初，1 是列表的 head。现在，将 new 插入到节点 1 之前，使得节点 1 的前驱指向 new。将 new 设为列表的 head，其前驱指向 null。

算法

定义一个 Node 类，它表示列表中的一个节点。它将有三个属性：数据、previous 指向前一个节点，以及 next 指向下一个节点。
定义另一个用于创建双向链表的类，它有两个节点：头节点和尾节点。最初，头节点和尾节点将指向 null。
addAtStart() 将向列表开头添加一个节点
1. 它首先检查头节点是否为 null，然后将节点作为头节点插入。
2. 头节点和尾节点都将指向新添加的节点。
3. 头节点的前一个指针将指向 null，尾节点的下一个指针将指向 null。
4. 如果 head 不为 null，则 head 的前驱将指向新节点。
5. 将新节点设为列表的 head。
6. 由于新节点成为了 head，所以它的前驱应该指向 null。
display() 将显示列表中存在的所有节点。
1. 定义一个新节点“current”，它将指向头节点。
2. 打印 current.data 直到 current 指向 null。
3. 在每次迭代中，current 将指向列表中的下一个节点。

解决方案

Python

#Represent a node of doubly linked list
class Node:
    def __init__(self,data):
        self.data = data;
        self.previous = None;
        self.next = None;
        
class InsertStart:
    #Represent the head and tail of the doubly linked list
    def __init__(self):
        self.head = None;
        self.tail = None;
        
    #addAtStart() will add a node to the starting of the list
    def addAtStart(self, data):
        #Create a new node
        newNode = Node(data);
        
        #If list is empty
        if(self.head == None):
            #Both head and tail will point to newNode
            self.head = self.tail = newNode;
            #head's previous will point to None
            self.head.previous = None;
            #tail's next will point to None, as it is the last node of the list
            self.tail.next = None;
        #Add newNode as new head of the list
        else:
            #head's previous node will be newNode
            self.head.previous = newNode;
            #newNode's next node will be head
            newNode.next = self.head;
            #newNode's previous will point to None
            newNode.previous = None;
            #newNode will become new head
            self.head = newNode;
            
    #display() will print out the nodes of the list
    def display(self):
        #Node current will point to head
        current = self.head;
        if(self.head == None):
            print("List is empty");
            return;
        print("Adding a node to the start of the list: ");
        while(current != None):
            #Prints each node by incrementing pointer.
            print(current.data),
            current = current.next;
            
        print();
        
dList = InsertStart();
 
#Adding 1 to the list
dList.addAtStart(1);
dList.display();
#Adding 2 to the list
dList.addAtStart(2);
dList.display();
#Adding 3 to the list
dList.addAtStart(3);
dList.display();
#Adding 4 to the list
dList.addAtStart(4);
dList.display();
#Adding 5 to the list
dList.addAtStart(5);
dList.display();

输出

Adding a node to the start of the list: 
1 
Adding a node to the start of the list: 
2 1 
Adding a node to the start of the list: 
3 2 1 
Adding a node to the start of the list: 
4 3 2 1 
Adding a node to the start of the list: 
5 4 3 2 1

C

#include <stdio.h>
 
//Represent a node of the doubly linked list

struct node{
    int data;
    struct node *previous;
    struct node *next;
};    
 
//Represent the head and tail of the doubly linked list
struct node *head, *tail = NULL;
 
//addAtStart() will add a node to the starting of the list
void addAtStart(int data) {
    //Create a new node
    struct node *newNode = (struct node*)malloc(sizeof(struct node));
    newNode->data = data;
    
    //If list is empty
    if(head == NULL) {
        //Both head and tail will point to newNode
        head = tail = newNode;
        //head's previous will point to NULL
        head->previous = NULL;
        //tail's next will point to NULL, as it is the last node of the list
        tail->next = NULL;
    }
    //Add newNode as new head of the list
    else {
        //head's previous node will be newNode
        head->previous = newNode;
        //newNode's next node will be head
        newNode->next = head;
        //newNode's previous will point to NULL
        newNode->previous = NULL;
        //newNode will become new head
        head = newNode;
    }
}
 
//display() will print out the nodes of the list
void display() {
    //Node current will point to head
    struct node *current = head;
    if(head == NULL) {
        printf("List is empty\n");
        return;
    }
    printf("Adding a node to the start of the list: \n");
    while(current != NULL) {
        //Prints each node by incrementing pointer.
        printf("%d ", current->data);
        current = current->next;
    }
    printf("\n");
}
 
int main()
{
    //Adding 1 to the list
    addAtStart(1);
    display();
    //Adding 2 to the list
    addAtStart(2);
    display();
    //Adding 3 to the list
    addAtStart(3);
    display();
    //Adding 4 to the list
    addAtStart(4);
    display();
    //Adding 5 to the list
    addAtStart(5);
    display();
 
    return 0;
}

输出

Adding a node to the start of the list: 
1 
Adding a node to the start of the list: 
2 1 
Adding a node to the start of the list: 
3 2 1 
Adding a node to the start of the list: 
4 3 2 1 
Adding a node to the start of the list: 
5 4 3 2 1

JAVA

public class InsertStart {
    
    //Represent a node of the doubly linked list

    class Node{
        int data;
        Node previous;
        Node next;
        
        public Node(int data) {
            this.data = data;
        }
    }
    
    //Represent the head and tail of the doubly linked list
    Node head, tail = null;
    
    //addAtStart() will add a node to the starting of the list
    public void addAtStart(int data) {
        //Create a new node
        Node newNode = new Node(data);
        
        //If list is empty
        if(head == null) {
            //Both head and tail will point to newNode
            head = tail = newNode;
            //head's previous will point to null
            head.previous = null;
            //tail's next will point to null, as it is the last node of the list
            tail.next = null;
        }
        //Add newNode as new head of the list
        else {
            //head's previous node will be newNode
            head.previous = newNode;
            //newNode's next node will be head
            newNode.next = head;
            //newNode's previous will point to null
            newNode.previous = null;
            //newNode will become new head
            head = newNode;
        }
    }
    
    //display() will print out the nodes of the list
    public void display() {
        //Node current will point to head
        Node current = head;
        if(head == null) {
            System.out.println("List is empty");
            return;
        }
        System.out.println("Adding a node to the start of the list: ");
        while(current != null) {
            //Prints each node by incrementing the pointer.

            System.out.print(current.data + " ");
            current = current.next;
        }
        System.out.println();
    }
    
    public static void main(String[] args) {
        
        InsertStart dList = new InsertStart();
        
        //Adding 1 to the list
        dList.addAtStart(1);
        dList.display();
        //Adding 2 to the list
        dList.addAtStart(2);
        dList.display();
        //Adding 3 to the list
        dList.addAtStart(3);
        dList.display();
        //Adding 4 to the list
        dList.addAtStart(4);
        dList.display();
        //Adding 5 to the list
        dList.addAtStart(5);
        dList.display();
    }
}

输出

Adding a node to the start of the list: 
1 
Adding a node to the start of the list: 
2 1 
Adding a node to the start of the list: 
3 2 1 
Adding a node to the start of the list: 
4 3 2 1 
Adding a node to the start of the list: 
5 4 3 2 1

C#

 using System; 
namespace DoublyLinkedList 
{                     
    public class Program
    {
        //Represent a node of the doubly linked list

        public class Node<T>{
            public T data;
            public Node<T> previous;
            public Node<T> next;
            
            public Node(T value) {
                data = value;
            }
        }
        
        public class InsertStart<T>{
            //Represent the head and tail of the doubly linked list
            protected Node<T> head = null;             
             protected Node<T> tail = null;
            
            //addAtStart() will add a node to the starting of the list
            public void addAtStart(T data) {
                //Create a new node
                Node<T> newNode = new Node<T>(data);
 
                //If list is empty
                if(head == null) {
                    //Both head and tail will point to newNode
                    head = tail = newNode;
                    //head's previous will point to null
                    head.previous = null;
                    //tail's next will point to null, as it is the last node of the list
                    tail.next = null;
                }
                //Add newNode as new head of the list
                else {
                    //head's previous node will be newNode
                    head.previous = newNode;
                    //newNode's next node will be head
                    newNode.next = head;
                    //newNode's previous will point to null
                    newNode.previous = null;
                    //newNode will become new head
                    head = newNode;
                }
            }
    
            //display() will print out the nodes of the list
            public void display() {
                //Node current will point to head
                Node<T> current = head;
                if(head == null) {
                    Console.WriteLine("List is empty");
                    return;
                }
                Console.WriteLine("Adding a node to the start of the list: ");
                while(current != null) {
                    //Prints each node by incrementing the pointer.

                    Console.Write(current.data + " ");
                    current = current.next;
                }
                Console.WriteLine();
            }
        }
        
        public static void Main()
        {
            InsertStart<int> dList = new InsertStart<int>();
 
            //Adding 1 to the list
            dList.addAtStart(1);
            dList.display();
            //Adding 2 to the list
            dList.addAtStart(2);
            dList.display();
            //Adding 3 to the list
            dList.addAtStart(3);
            dList.display();
            //Adding 4 to the list
            dList.addAtStart(4);
            dList.display();
            //Adding 5 to the list
            dList.addAtStart(5);
            dList.display();
        }    
    }
}

输出

Adding a node to the start of the list: 
1 
Adding a node to the start of the list: 
2 1 
Adding a node to the start of the list: 
3 2 1 
Adding a node to the start of the list: 
4 3 2 1 
Adding a node to the start of the list: 
5 4 3 2 1

PHP

<!DOCTYPE html>
<html>
<body>
<?php
//Represent a node of doubly linked list
class Node{
    public $data;
    public $previous;
    public $next;
    
    function __construct($data){
        $this->data = $data;
    }
}
class InsertStart{
    //Represent the head and tail of the doubly linked list
    public $head;
    public $tail;
    function __construct(){
        $this->head = NULL;
        $this->tail = NULL;
    }
    
    //addAtStart() will add a node to the starting of the list
    function addAtStart($data) {
        //Create a new node
        $newNode = new Node($data);
        
        //If list is empty
        if($this->head == NULL) {
            //Both head and tail will point to newNode
            $this->head = $this->tail = $newNode;
            //head's previous will point to NULL
            $this->head->previous = NULL;
            //tail's next will point to NULL, as it is the last node of the list
            $this->tail->next = NULL;
        }
        //Add newNode as new head of the list
        else {
            //head's previous node will be newNode
            $this->head->previous = $newNode;
            //newNode's next node will be head
            $newNode->next = $this->head;
            //newNode's previous will point to NULL
            $newNode->previous = NULL;
            //newNode will become new head
            $this->head = $newNode;
        }
    }
    
    //display() will print out the nodes of the list
    function display() {
        //Node current will point to head
        $current = $this->head;
        if($this->head == NULL) {
            print("List is empty <br>");
            return;
        }
        print("Adding a node to the start of the list: <br>");
        while($current != NULL) {
            //Prints each node by incrementing pointer.
            print($current->data . " ");
            $current = $current->next;
        }
        print("<br>");
    }
}
    
$dList = new InsertStart();
 
//Adding 1 to the list
$dList->addAtStart(1);
$dList->display();
//Adding 2 to the list
$dList->addAtStart(2);
$dList->display();
//Adding 3 to the list
$dList->addAtStart(3);
$dList->display();
//Adding 4 to the list
$dList->addAtStart(4);
$dList->display();
//Adding 5 to the list
$dList->addAtStart(5);
$dList->display();
?>
</body>
</html>

输出

Adding a node to the start of the list: 
1 
Adding a node to the start of the list: 
2 1 
Adding a node to the start of the list: 
3 2 1 
Adding a node to the start of the list: 
4 3 2 1 
Adding a node to the start of the list: 
5 4 3 2 1

下一主题#

问：在双向链表的开头插入新节点的程序。

说明

算法

解决方案

Python

C

JAVA

C#

PHP

联系信息

关注我们

教程

面试题

在线编译器

Python

Java

.Net Framework

AI, ML and Data Science

Cloud Technology

B.Tech and MCA

Web Technology

PHP

Software Testing

Technical Interview

Java Interview

Python

Web Interview

Database Interview

B.Tech / MCA

Important Interview

Software Testing Interview

Company Interviews

Online Compilers

Multiple Choice Questions

程序

问：在双向链表的开头插入新节点的程序。

说明

算法

解决方案

Python

C

JAVA

C#

PHP

相关帖子

在循环链表末尾插入新节点的程序

创建和显示单向链表的程序

计算圆锥体积的程序

编写查找三棱柱（Triangular Prism）表面积的程序

单向链表示例

打印数字图案 17 的程序

将英尺转换为米的程序

创建包含 N 个节点的循环链表并计算节点数量的程序

查找数组中每个元素出现频率的程序

创建和显示循环链表的程序

订阅 Tpoint Tech

联系信息

关注我们

教程

面试题

在线编译器