从单向链表中删除中间节点的程序

2025年3月17日 | 阅读 12 分钟

说明

在此程序中，我们将创建一个单链表并从列表中间删除一个节点。为完成此任务，我们将计算列表的大小，然后将其除以 2 以获得列表的中间点。节点 temp 将指向头节点。我们将遍历列表直到到达中间点。现在，temp 将指向中间节点，current 节点将指向 temp 的前一个节点。我们通过将 current 的下一个节点指向 temp 的下一个节点来删除中间节点。

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

以上面为例，上面列表的中间点是 2。将 temp 从头节点遍历到中间点。现在，temp 指向需要删除的中间节点。在这种情况下，Node 是需要删除的中间节点。可以通过使节点 2 的下一个节点（current）指向节点 3（temp 的下一个节点）来删除该节点。将 temp 设置为 null。

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 DeleteMid 的类，该类具有三个属性：head、tail 和 size，用于跟踪列表中存在的节点数。
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，head 和 tail 都将指向新添加的节点。
4. 如果列表不为空，新节点将被添加到列表的末尾，以便 tail 的 next 将指向新添加的节点。这个新节点将成为列表的新 tail。
deleteFromMid() 将从链表中删除中间节点
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，则计算列表的大小并将其除以 2 以获得列表的中间点。
5. 声明一个节点 temp，它将指向 head，以及一个节点 current，它将指向 temp 的前一个节点。
6. 遍历列表直到 temp 指向中间节点。如果 current 不指向 null，则通过使 current 的下一个节点指向 temp 的下一个节点来删除中间节点（temp）。否则，head 和 tail 都将指向 temp 的下一个节点，并通过将 temp 设置为 null 来删除中间节点。
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 DeleteMid:
    #Represent the head and tail of the singly linked list
    def __init__(self):
        self.head = None;
        self.tail = None;
        self.size = 0;
        
    #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;
        #Size will count the number of nodes present in the list
        self.size = self.size + 1;
            
    #deleteFromMid() will delete a node from the middle of the list
    def deleteFromMid(self):
        #Checks if list is empty
        if(self.head == None):
            print("List is empty");
            return;
        else:
            #Store the mid position of the list
            count = (self.size//2) if(self.size % 2 == 0)  else((self.size+1)//2);
            
            #Checks whether head is equal to tail or not, if yes then list has only one node.
            if( self.head != self.tail ):
                #Initially, temp will point to head
                temp = self.head;
                current = None;
                
                #Current will point to node previous to
                #If temp is pointing to node 2 then current will point to node 1.
                for i in range(0, count-1):
                    current = temp;
                    temp = temp.next;
                    
                if(current != None):
                    #temp is the middle that needs to be removed.
                    #So, current node will point to node next to temp by skipping temp.
                    current.next = temp.next;
                    #Delete temp
                    temp = None;
                #If current points to None then, head and tail will point to node next to temp.
                else:
                    self.head = self.tail = temp.next;
                    #Delete temp
                    temp = None;
            #If the list contains only one element
            #then it will remove it and both head and tail will point to None
            else:
                self.head = self.tail = None;
        self.size = self.size - 1;
                
    #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),
            current = current.next;

sList = DeleteMid();
 
#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.deleteFromMid();
    #Printing updated list
    print("Updated List: ");
    sList.display();

输出

Original List: 
1 2 3 4 
Updated List: 
1 3 4 
Updated List: 
1 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;
};    
 
int size;
//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;
    }
    //Size will count the number of nodes present in the list
    size++;
}
 
//deleteFromMid() will delete a node from the middle of the list
void deleteFromMid() {
    struct node *temp, *current;
    
    //Checks if list is empty
    if(head == NULL) {
        printf("List is empty \n");
        return;
    }
    else {
        //Store the mid position of the list
        int count = (size % 2 == 0) ? (size/2) : ((size+1)/2);
        
        //Checks whether the head is equal to the tail or not, if yes then the list has only one node.
        if( head != tail ) {
            //Initially, temp will point to head
            temp = head;
            current = NULL;
            
            //Current will point to node previous to temp
            //If temp is pointing to node 2 then current will point to node 1.
            for(int i = 0; i < count-1; i++){
                current = temp;
                temp = temp->next;
            }                
            if(current != NULL) {
                //temp is the middle that needs to be removed.
                //So, current node will point to node next to temp by skipping temp.
                current->next = temp->next;
                //Delete temp
                temp = NULL;
            }
            //If current points to NULL then, head and tail will point to node next to temp.
            else {
                head = tail = temp->next;
                //Delete temp
                temp = NULL;
            }    
        }
        //If the list contains only one element 
        //then it will remove it and both head and tail will point to NULL
        else {
            head = tail = NULL;
        }
    }
    size--;
}
    
//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) {
        deleteFromMid();
        //Printing updated list
        printf("Updated List: \n");
        display();
    }
        
    return 0;
}

输出

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

JAVA

#include <stdio.h>
 
//Represent a node of the singly linked list
struct node{
    int data;
    struct node *next;
};    
 
int size;
//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;
    }
    //Size will count the number of nodes present in the list
    size++;
}
 
//deleteFromMid() will delete a node from the middle of the list
void deleteFromMid() {
    struct node *temp, *current;
    
    //Checks if list is empty
    if(head == NULL) {
        printf("List is empty \n");
        return;
    }
    else {
        //Store the mid position of the list
        int count = (size % 2 == 0) ? (size/2) : ((size+1)/2);
        
        //Checks whether the head is equal to the tail or not, if yes then the list has only one node.
        if( head != tail ) {
            //Initially, temp will point to head
            temp = head;
            current = NULL;
            
            //Current will point to node previous to temp
            //If temp is pointing to node 2 then current will point to node 1.
            for(int i = 0; i < count-1; i++){
                current = temp;
                temp = temp->next;
            }                
            if(current != NULL) {
                //temp is the middle that needs to be removed.
                //So, current node will point to node next to temp by skipping temp.
                current->next = temp->next;
                //Delete temp
                temp = NULL;
            }
            //If current points to NULL then, head and tail will point to node next to temp.
            else {
                head = tail = temp->next;
                //Delete temp
                temp = NULL;
            }    
        }
        //If the list contains only one element 
        //then it will remove it and both head and tail will point to NULL
        else {
            head = tail = NULL;
        }
    }
    size--;
}
    
//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) {
        deleteFromMid();
        //Printing updated list
        printf("Updated List: \n");
        display();
    }
        
    return 0;
}

输出

Original List: 
1 2 3 4 
Updated List: 
1 3 4 
Updated List: 
1 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 DeleteMid<T>{
        public int size;
        //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;
            }
            //Size will count the number of nodes present in the list
            size++;
        }
    
        //deleteFromMid() will delete a node from the middle of the list
        public void deleteFromMid() {
            Node<T> temp, current;
 
            //Checks if list is empty
            if(head == null) {
                Console.WriteLine("List is empty");
                return;
            }
            else {
                //Store the mid position of the list
                int count = (size % 2 == 0) ? (size/2) : ((size+1)/2);
 
                //Checks whether the head is equal to the tail or not, if yes then the list has only one node.
                if( head != tail ) {
                    //Initially, temp will point to head
                    temp = head;
                    current = null;
 
                    //Current will point to node previous to temp
                    //If temp is pointing to node 2 then current will point to node 1.
                    for(int i = 0; i < count-1; i++){
                        current = temp;
                        temp = temp.next;
                    }                
                    if(current != null) {
                        //temp is the middle that needs to be removed.
                        //So, current node will point to node next to temp by skipping temp.
                        current.next = temp.next;
                        //Delete temp
                      temp = null;
                    }
                    //If current points to null then, head and tail will point to node next to temp.
                    else {
                        head = tail = temp.next;
                        //Delete temp
                        temp = null;
                    }    
                }
                //If the list contains only one element 
                //then it will remove it and both head and tail will point to null
                else {
                    head = tail = null;
                }
            }
            size--;
        }
        
        //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()
    {
        DeleteMid<int> sList = new DeleteMid<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.deleteFromMid();
            //Printing updated list
            Console.WriteLine("Updated List: ");
            sList.display();
        }
    }
}

输出

Original List: 
1 2 3 4 
Updated List: 
1 3 4 
Updated List: 
1 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 DeleteMid{
    //Represent the head and tail of the singly linked list
    public $head;
    public $tail;
    function __construct(){
        $this->head = NULL;
        $this->tail = NULL;
        $this->size = 0;
    }
    
    //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;
        }
        //Size will count the number of nodes present in the list
        $this->size++;
    }
    
    //deleteFromMid() will delete a node from the middle of the list
    function deleteFromMid() {
        
        //Checks if list is empty
        if($this->head == null) {
            print("List is empty <br>");
            return;
        }
        else {
            //Store the mid position of the list
            $count = ($this->size % 2 == 0) ? ($this->size/2) : (($this->size+1)/2);
            
            //Checks whether head is equal to tail or not, if yes then list has only one node.
            if( $this->head != $this->tail ) {
                //Initially, temp will point to head
                $temp = $this->head;
                $current = null;
                
                //Current will point to node previous to temp
                //If temp is pointing to node 2 then current will point to node 1.
                for($i = 0; $i < $count-1; $i++){
                    $current = $temp;
                    $temp = $temp->next;
                }                
                if($current != null) {
                    //temp is the middle that needs to be removed.
                    //So, current node will point to node next to temp by skipping temp.
                    $current->next = $temp->next;
                    //Delete temp
                    $temp = null;
                }
                //If current points to null then, head and tail will point to node next to temp.
                else {
                    $this->head = $this->tail = $temp->next;
                    //Delete temp
                    $temp = null;
                }    
            }
            //If the list contains only one element 
            //then it will remove it and both head and tail will point to null
            else {
                $this->head = $this->tail = null;
            }
        }
        $this->size--;
    }
    
    //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 DeleteMid();
        
//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->deleteFromMid();
    //Printing updated list
    print("Updated List: <br>");
    $sList->display();
}
?>
</body>
</html>

输出

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

下一主题#

从单向链表中删除中间节点的程序

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