数据结构示例-从头部删除单链表节点

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📜 数据结构示例-从头部删除单链表节点

📅 最后修改于: 2020-10-15 01:51:22 🧑 作者: Mango

从单链列表的开头删除新节点的程序

说明

在此程序中，我们将创建一个单链列表，并从列表的开头删除一个节点。要完成此任务，我们需要使头指针指向初始节点的直接下一个节点，该节点现在将成为列表的新头节点。

考虑上面的例子； Node是列表的头。使头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，删除节点。

算法

创建一个具有两个属性的类Node：data和next。下一个是指向列表中下一个节点的指针。
创建另一个类DeleteStart，它具有两个属性：head和tail。
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，则头和尾都将指向新添加的节点。
4. 如果列表不为空，则新节点将被添加到列表的末尾，使得尾部的下一个将指向新添加的节点。这个新节点将成为列表的新尾部。
deleteFromStart()将从列表的开头删除一个节点：
1. 它首先检查头是否为空(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，则它将head和tail都设置为null。
4. 如果列表中有多个节点，那么头将指向列表中的下一个节点并删除旧的头节点。
display()将显示列表中存在的节点：
1. 定义一个节点电流，该电流将初始指向列表的开头。
2. 遍历列表，直到当前指向null。
3. 通过在每次迭代中使电流指向其旁边的节点来显示每个节点。

示例：

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 
 
//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{
        public T data;
        public Node next;
        
        public Node(T value) {
            data = value;
            next = null;
        }
    }
        
    public class DeleteStart{
        //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(T 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) {
                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 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 sList = new DeleteStart();
        
        //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：




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($this->head == null) {
            print("List is empty 
");
            return;
        }
        else {
            //Checks whether the list contains only one node
            //If not, head will point to next node in the list and tail will point to new head.
            if($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($this->head == NULL) {
            print("List is empty 
");
            return;
        }
        while($current != NULL) {
            //Prints each node by incrementing pointer
            print($current->data . " ");
            $current = $current->next;
        }
        print("
");
    }
}
 
$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: 
");
$sList->display();
 
while($sList->head != null) {
    $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