在单链表中搜索元素的程序

2025年3月17日 | 阅读 7 分钟

说明

在此程序中，我们需要在给定的单链表中搜索一个节点。

Program to search an element in a singly linked list

要解决此问题，我们将使用一个名为 current 的节点遍历列表。Current 指向 head，并开始将要搜索的节点数据与当前节点数据进行比较。如果它们相等，则将标志设置为 true，并打印消息以及要搜索的节点的位置。

例如，在上面的列表中，搜索的节点是4，可以在位置4找到。

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。
创建另一个类SearchLinkedList，它有两个属性：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 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。
searchNode()将搜索列表中的一个节点
1. 变量 i 将跟踪要搜索节点的**位置**。
2. 变量 flag 将存储布尔值 false。
3. Node current将指向head节点。
4. 通过将 current 递增到 current.next 并将 i 递增到 i + 1 来迭代循环。
5. 将每个节点的数据与搜索的节点进行比较。如果找到匹配项，则将 flag 设置为 true。
6. 如果标志为true，则显示被搜索节点的所在位置。
7. 否则，显示消息“元素不在列表中”。
display() 将显示列表中存在的节点
1. 定义一个节点current，它将最初指向列表的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 SearchLinkedList:
    #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;
            
    #searchNode() will search for a given node in the list
    def searchNode(self, data):
        current = self.head;
        i = 1;
        flag = False;
        
        #Checks whether list is empty
        if(self.head == None):
            print("List is empty");
        else:
            while(current != None):
                #Compares node to be found with each node present in the list
                if(current.data == data):
                    flag = True;
                    break;
                i=i+1;
                current = current.next;
        if(flag):
            print("Element is present in the list at the position : " + str(i));
        else:
            print("Element is not present in the list");
 
sList = SearchLinkedList();
 
#Add nodes to the list
sList.addNode(1);
sList.addNode(2);
sList.addNode(3);
sList.addNode(4);
 
#Search for node 2 in the list
sList.searchNode(2);
#Search for the node  in the list
sList.searchNode(7);

输出

Element is present in the list at the position : 2
Element is not present in the list

C

#include <stdio.h>
#include <stdbool.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;
    }
}
 
//searchNode() will search for a given node in the list
void searchNode(int data) {
    struct node *current = head;
    int i = 1;
    bool flag = false;
    
    //Checks whether list is empty
    if(head == NULL) {
        printf("List is empty \n");
    }
    else {
        while(current != NULL) {
             //Compares node to be found with each node present in the list
            if(current->data == data) {
                flag = true;
                break;
            }
            i++;
            current = current->next;
        }
    }
    if(flag)
         printf("Element is present in the list at the position: %d\n", i);
    else
         printf("Element is not present in the list\n");
}
    
int main()
{
    //Add nodes to the list
    addNode(1);
    addNode(2);
    addNode(3);
    addNode(4);
    
    //Search for node 2 in the list
    searchNode(2);
    //Search for node  in the list
    searchNode(7);
        
    return 0;
}

输出

Element is present in the list at the position : 2
Element is not present in the list

JAVA

public class SearchLinkedList {
    
    //Represent a node of 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;
        }
    }
    
    //searchNode() will search for a given node in the list
    public void searchNode(int data) {
        Node current = head;
        int i = 1;
        boolean flag = false;
        
        //Checks whether list is empty
        if(head == null) {
            System.out.println("List is empty");
        }
        else {
            while(current != null) {
                 //Compares node to be found with each node present in the list
                if(current.data == data) {
                    flag = true;
                    break;
                }
                i++;
                current = current.next;
            }
        }
        if(flag)
             System.out.println("Element is present in the list at the position : " + i);
        else
             System.out.println("Element is not present in the list");
    }
    
    public static void main(String[] args) {
        
        SearchLinkedList sList = new SearchLinkedList();
        
        //Add nodes to the list
        sList.addNode(1);
        sList.addNode(2);
        sList.addNode(3);
        sList.addNode(4);
        
        //Search for node 2 in the list
        sList.searchNode(2);
        //Search for a node  in the list
        sList.searchNode(7);
    }
}

输出

Element is present in the list at the position : 2
Element is not present in the list

C#

using System;
                    
public class CreateList
{
    //Represent a node of singly linked list
    public class Node<T>{
        public T data;
        public Node<T> next;
        
        public Node(T value) {
            data = value;
            next = null;
        }
    }
        
    public class SearchLinkedList<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;
            }
        }
    
        //searchNode() will search for a given node in the list
        public void searchNode(T data) {
            Node<T> current = head;
            int i = 1;
            Boolean flag = false;
 
            //Checks whether list is empty
            if(head == null) {
                Console.WriteLine("List is empty");
            }
            else {
                while(current != null) {
                     //Compares node to be found with each node present in the list
                    if(current.data.Equals(data)) {
                        flag = true;
                        break;
                    }
                    i++;
                    current = current.next;
                }
            }
            if(flag)
                 Console.WriteLine("Element is present in the list at the position : " + i);
            else
                 Console.WriteLine("Element is not present in the list");
        }
    }
    
    public static void Main()
    {
        SearchLinkedList<int> sList = new SearchLinkedList<int>();
        
        //Add nodes to the list
        sList.addNode(1);
        sList.addNode(2);
        sList.addNode(3);
        sList.addNode(4);
        
        //Search for node 2 in the list
        sList.searchNode(2);
        //Search for a node  in the list
        sList.searchNode(7);
    }
}

输出

Element is present in the list at the position : 2
Element is not present in the list

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 SearchLinkedList{
    //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;
        }
    }
    
    //searchNode() will search for a given node in the list
    function searchNode($data) {
        $current = $this->head;
        $i = 1;
        $flag = false;
        
        //Checks whether list is empty
        if($this->head == null) {
            print("List is empty<br>");
        }
        else {
            while($current != null) {
                 //Compares node to be found with each node present in the list
                if($current->data == $data) {
                    $flag = true;
                    break;
                }
                $i++;
                $current = $current->next;
            }
        }
        if($flag)
             print("Element is present in the list at the position : " . $i);
        else
             print("<br>Element is not present in the list");
    }
}
    
$sList = new SearchLinkedList();
        
//Add nodes to the list
$sList->addNode(1);
$sList->addNode(2);
$sList->addNode(3);
$sList->addNode(4);
 
//Search for node 2 in the list
$sList->searchNode(2);
//Search for node  in the list
$sList->searchNode(7);
?>
</body>
</html>

输出

Element is present in the list at the position : 2
Element is not present in the list

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在单链表中搜索元素的程序

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在单链表中搜索元素的程序

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