从单链表开头删除新节点的程序

2025年03月17日 | 阅读 9 分钟

说明

在此程序中，我们将创建一个单链表并从列表的开头删除一个节点。要完成此任务，我们需要将头指针指向初始节点的下一个节点，该节点将成为列表的新头节点。

Program to delete a new node from the beginning of the singly linked list

考虑上面的例子；Node 是列表的头。将 head 指向列表中的下一个节点。现在，节点 1 将成为列表的新头。因此，删除 Node。

算法

创建一个名为 Node 的类，它有两个属性：data 和 next。Next 是指向链表中下一个节点的指针。
创建另一个名为 DeleteStart 的类，该类具有 head 和 tail 两个属性。
addNode() 将向列表添加一个新节点
1. 创建一个新节点。
2. 它首先检查 head 是否等于 null，这意味着列表为空。
3. 如果列表为空，则 head 和 tail 都将指向新添加的节点。
4. 如果列表不为空，新节点将添加到列表末尾，使得 tail 的 next 指向新添加的节点。此新节点将成为列表的新 tail。
deleteFromStart() 将从列表开头删除一个节点
1. 它首先检查 head 是否为 null（空列表），然后显示消息“列表为空”并返回。
2. 如果列表不为空，它将检查列表是否只有一个节点。
3. 如果列表只有一个节点，它将 head 和 tail 都设置为 null。
4. 如果列表包含多个节点，则头部将指向列表中的下一个节点，并删除旧的头部节点。
display() 将显示列表中存在的节点
1. 定义一个节点 current，它最初将指向列表的 head。
2. 遍历列表直到 current 指向 null。
3. 通过使 current 在每次迭代中指向它的下一个节点来显示每个节点。

解决方案

Python

#Represent a node of the singly linked list
class Node:
    def __init__(self,data):
        self.data = data;
        self.next = None;
        
class DeleteStart:
    #Represent the head and tail of the singly linked list
    def __init__(self):
        self.head = None;
        self.tail = None;
        
    #addNode() will add a new node to the list
    def addNode(self, data):
        #Create a new node
        newNode = Node(data);
        
        #Checks if the list is empty
        if(self.head == None):
            #If list is empty, both head and tail will point to new node
            self.head = newNode;
            self.tail = newNode;
        else:
            #newNode will be added after tail such that tail's next will point to newNode
            self.tail.next = newNode;
            #newNode will become new tail of the list
            self.tail = newNode;
            
    #deleteFromStart() will delete a node from the beginning of the list
    def deleteFromStart(self):
        
        #Checks if the list is empty
        if(self.head == None):
            printf("List is empty\n");
            return;
        else:
            #Checks whether the list contains only one node
            #If not, head will point to next node in the list and tail will point to new head.
            if(self.head != self.tail):
                self.head = self.head.next;
                #If the list contains only one node
                #then, it will remove it and both head and tail will point to None
            else:
                self.head = self.tail = None;
                
    #display() will display all the nodes present in the list
    def display(self):
        #Node current will point to head
        current = self.head;
        if(self.head == None):
            print("List is empty");
            return;
        while(current != None):
            #Prints each node by incrementing pointer
            print(current.data, end=" ");
            current = current.next;
        print();
 
sList =  DeleteStart();
 
#Adds data to the list
sList.addNode(1);
sList.addNode(2);
sList.addNode(3);
sList.addNode(4);
#Printing original list
print("Original List: ");
sList.display();
 
while(sList.head != None):
    sList.deleteFromStart();
    #Printing updated list
    print("Updated List: ");
    sList.display();

输出

 Original List: 
1 2 3 4 
Updated List: 
2 3 4 
Updated List: 
3 4 
Updated List: 
4 
Updated List: 
List is empty

C

#include <stdio.h>
 
//Represent a node of the singly linked list
struct node{
    int data;
    struct node *next;
};    
 
//Represent the head and tail of the singly linked list
struct node *head, *tail = NULL;
 
//addNode() will add a new node to the list
void addNode(int data) {
    //Create a new node
    struct node *newNode = (struct node*)malloc(sizeof(struct node));
    newNode->data = data;
    newNode->next = NULL;
    
    //Checks if the list is empty
    if(head == NULL) {
        //If list is empty, both head and tail will point to new node
        head = newNode;
        tail = newNode;
    }
    else {
        //newNode will be added after tail such that tail's next will point to newNode
        tail->next = newNode;
        //newNode will become new tail of the list
        tail = newNode;
    }
}
 
//deleteFromStart() will delete a node from the beginning of the list
void deleteFromStart() {
    
    //Checks if the list is empty
    if(head == NULL) {
        printf("List is empty \n");
        return;
    }
    else {
        //Checks whether the list contains only one node
        //If not, the head will point to next node in the list and tail will point to the new head.
        if(head != tail) {
            head = head->next;
        }
        //If the list contains only one node 
        //then, it will remove it and both head and tail will point to NULL
        else {
            head = tail = NULL;
        }
    }
}
    
//display() will display all the nodes present in the list
void display() {
    //Node current will point to head
    struct node *current = head;
    if(head == NULL) {
        printf("List is empty\n");
        return;
    }
    while(current != NULL) {
        //Prints each node by incrementing pointer
        printf("%d ", current->data);
        current = current->next;
    }
    printf("\n");
}
    
int main()
{
    //Adds data to the list
    addNode(1);
    addNode(2);
    addNode(3);
    addNode(4);
    
    //Printing original list
    printf("Original List: \n");
    display();
    
    while(head != NULL) {
        deleteFromStart();
        //Printing updated list
        printf("Updated List: \n");
        display();
    }
 
    return 0;
}

输出

Original List: 
1 2 3 4 
Updated List: 
2 3 4 
Updated List: 
3 4 
Updated List: 
4 
Updated List: 
List is empty

JAVA

public class DeleteStart {
    
    //Represent a node of the singly linked list
    class Node{
        int data;
        Node next;
        
        public Node(int data) {
            this.data = data;
            this.next = null;
        }
    }
 
    //Represent the head and tail of the singly linked list
    public Node head = null;
    public Node tail = null;
    
    //addNode() will add a new node to the list
    public void addNode(int data) {
        //Create a new node
        Node newNode = new Node(data);
        
        //Checks if the list is empty
        if(head == null) {
            //If list is empty, both head and tail will point to new node
            head = newNode;
            tail = newNode;
        }
        else {
            //newNode will be added after tail such that tail's next will point to newNode
            tail.next = newNode;
            //newNode will become new tail of the list
            tail = newNode;
        }
    }
    
    //deleteFromStart() will delete a node from the beginning of the list
    public void deleteFromStart() {
        
        //Checks if the list is empty
        if(head == null) {
            System.out.println("List is empty");
            return;
        }
        else {
            //Checks whether the list contains only one node
            //If not, the head will point to next node in the list and tail will point to the new head.
            if(head != tail) {
                head = head.next;
            }
            //If the list contains only one node 
            //then, it will remove it and both head and tail will point to null
            else {
                head = tail = null;
            }
        }
    }
        
    //display() will display all the nodes present in the list
    public void display() {
        //Node current will point to head
        Node current = head;
        if(head == null) {
            System.out.println("List is empty");
            return;
        }
        while(current != null) {
            //Prints each node by incrementing pointer
            System.out.print(current.data + " ");
            current = current.next;
        }
        System.out.println();
    }
    
    public static void main(String[] args) {
        
        DeleteStart sList = new DeleteStart();
        
        //Adds data to the list
        sList.addNode(1);
        sList.addNode(2);
        sList.addNode(3);
        sList.addNode(4);
        
        //Printing original list
        System.out.println("Original List: ");
        sList.display();
        
        while(sList.head != null) {
            sList.deleteFromStart();
            //Printing updated list
            System.out.println("Updated List: ");
            sList.display();
        }
    }
}

输出

Original List: 
1 2 3 4 
Updated List: 
2 3 4 
Updated List: 
3 4 
Updated List: 
4 
Updated List: 
List is empty

C#

 using System;
                    
public class CreateList
{
    //Represent a node of the singly linked list
    public class Node<T>{
        public T data;
        public Node<T> next;
        
        public Node(T value) {
            data = value;
            next = null;
        }
    }
        
    public class DeleteStart<T>{
        //Represent the head and tail of the singly linked list
        public Node<T> head = null;             
         public Node<T> tail = null;
    
        //addNode() will add a new node to the list
        public void addNode(T data) {
            //Create a new node
            Node<T> newNode = new Node<T>(data);
 
            //Checks if the list is empty
            if(head == null) {
                //If list is empty, both head and tail will point to new node
                head = newNode;
                tail = newNode;
            }
            else {
                //newNode will be added after tail such that tail's next will point to newNode
                tail.next = newNode;
                //newNode will become new tail of the list
                tail = newNode;
            }
        }
    
        //deleteFromStart() will delete a node from the beginning of the list
        public void deleteFromStart() {
 
            //Checks if the list is empty
            if(head == null) {
                Console.WriteLine("List is empty");
                return;
            }
            else {
                //Checks whether the list contains only one node
                //If not, the head will point to next node in the list and tail will point to the new head.
                if(head != tail) {
                    head = head.next;
                }
                //If the list contains only one node 
                //then, it will remove it and both head and tail will point to null
                else {
                    head = tail = null;
                }
            }
        }
        
        //display() will display all the nodes present in the list
        public void display() {
            //Node current will point to head
            Node<T> current = head;
            if(head == null) {
                Console.WriteLine("List is empty");
                return;
            }
            while(current != null) {
                //Prints each node by incrementing pointer
                Console.Write(current.data + " ");
                current = current.next;
            }
            Console.WriteLine();
        }
    }
    
    public static void Main()
    {
        DeleteStart<int> sList = new DeleteStart<int>();
        
        //Adds data to the list
        sList.addNode(1);
        sList.addNode(2);
        sList.addNode(3);
        sList.addNode(4);
        
        //Printing original list
        Console.WriteLine("Original List: ");
        sList.display();
        
        while(sList.head != null) {
            sList.deleteFromStart();
            //Printing updated list
            Console.WriteLine("Updated List: ");
            sList.display();
        }
    }
}

输出

Original List: 
1 2 3 4 
Updated List: 
2 3 4 
Updated List: 
3 4 
Updated List: 
4 
Updated List: 
List is empty

PHP

<!DOCTYPE html>
<html>
<body>
<?php
//Represent a node of singly linked list
class Node{
    public $data;
    public $next;
    
    function __construct($data){
        $this->data = $data;
        $this->next = NULL;
    }
}
class DeleteStart{
    //Represent the head and tail of the singly linked list
    public $head;
    public $tail;
    function __construct(){
        $this->head = NULL;
        $this->tail = NULL;
    }
    
    //addNode() will add a new node to the list
    function addNode($data) {
        //Create a new node
        $newNode = new Node($data);
        
        //Checks if the list is empty
        if($this->head == null) {
            //If list is empty, both head and tail will point to new node
            $this->head = $newNode;
            $this->tail = $newNode;
        }
        else {
            //newNode will be added after tail such that tail's next will point to newNode
            $this->tail->next = $newNode;
            //newNode will become new tail of the list
            $this->tail = $newNode;
        }
    }
    
    //deleteFromStart() will delete a node from the beginning of the list
    function deleteFromStart() {
        
        //Checks if the list is empty
        if($this->head == null) {
            print("List is empty <br>");
            return;
        }
        else {
            //Checks whether the list contains only one node
            //If not, head will point to next node in the list and tail will point to new head.
            if($this->head != $this->tail) {
                $this->head = $this->head->next;
            }
            //If the list contains only one node 
            //then, it will remove it and both head and tail will point to null
            else {
                $this->head = $this->tail = null;
            }
        }
    }
    
    //display() will display all the nodes present in the list
    function display() {
        //Node current will point to head
        $current = $this->head;
        
        if($this->head == NULL) {
            print("List is empty <br>");
            return;
        }
        while($current != NULL) {
            //Prints each node by incrementing pointer
            print($current->data . " ");
            $current = $current->next;
        }
        print("<br>");
    }
}
 
$sList = new DeleteStart();
        
//Adds data to the list
$sList->addNode(1);
$sList->addNode(2);
$sList->addNode(3);
$sList->addNode(4);
 
//Printing original list
print("Original List: <br>");
$sList->display();
 
while($sList->head != null) {
    $sList->deleteFromStart();
    //Printing updated list
    print("Updated List: <br>");
    $sList->display();
}
?>
</body>
</html>

输出

 Original List: 
1 2 3 4 
Updated List: 
2 3 4 
Updated List: 
3 4 
Updated List: 
4 
Updated List: 
List is empty

下一主题#

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