Q:

Program to search an element in a doubly linked list

belongs to collection: Doubly Linked List Programs

robaa
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2022-11-11
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Explanation

In this program, we need to search a given node in a doubly linked list.

To solve this problem, we will traverse through the list using a node current. Current points to head and start comparing searched node data with current node data. If they are equal, set the flag to true and print the message along with the position of the searched node.

For, eg. In above list, a search node says 4 can be found at the position 3.

 

Algorithm

  1. Define a Node class which represents a node in the list. It will have three properties: data, previous which will point to the previous node and next which will point to the next node.
  2. Define another class for creating a doubly linked list, and it has two nodes: head and tail. Initially, head and tail will point to null.
  3. addNode() will add node to the list:
    1. It first checks whether the head is null, then it will insert the node as the head.
    2. Both head and tail will point to a newly added node.
    3. Head's previous pointer will point to null and tail's next pointer will point to null.
    4. If the head is not null, the new node will be inserted at the end of the list such that new node's previous pointer will point to tail.
    5. The new node will become the new tail. Tail's next pointer will point to null.
  4. searchNode() will search for a node in the list:
    1. Variable i will keep track of the position of the searched node.
    2. The variable flag will store boolean value false.
    3. Current will point to head node.
    4. Iterate through the loop by incrementing current to current.next and i to i + 1.
    5. Compare each node's data with the searched node. If a match is found, set flag to true.
    6. If the flag is true, prints the position of the searched node.
    7. Else, print the message "Element is not present in the list".

Input:

 

#Add nodes to the list  

dList.addNode(1);  

dList.addNode(5);  

dList.addNode(4);  

dList.addNode(2);  

dList.addNode(3);  

Output:

Node is present in the list at the position : 3
Node is not present in the list
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robaa
2022-11-11
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Python

#Represent a node of doubly linked list  
class Node:  
    def __init__(self,data):  
        self.data = data;  
        self.previous = None;  
        self.next = None;  
          
class SearchList:  
    #Represent the head and tail of the doubly linked list  
    def __init__(self):  
        self.head = None;  
        self.tail = None;  
          
    #addNode() will add a node to the list  
    def addNode(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;  
        else:  
            #newNode will be added after tail such that tail's next will point to newNode  
            self.tail.next = newNode;  
            #newNode's previous will point to tail  
            newNode.previous = self.tail;  
            #newNode will become new tail  
            self.tail = newNode;  
            #As it is last node, tail's next will point to None  
            self.tail.next = None;  
              
    #searchNode() will search a given node in the list  
    def searchNode(self, value):  
        i = 1;  
        flag = False;  
        #Node current will point to head  
        current = self.head;  
          
        #Checks whether the list is empty  
        if(self.head == None):  
            print("List is empty");  
            return;  
              
        while(current != None):  
            #Compare value to be searched with each node in the list  
            if(current.data == value):  
                flag = True;  
                break;  
            current = current.next;  
            i = i + 1;  
              
        if(flag):  
            print("Node is present in the list at the position : " + str(i));  
        else:  
            print("Node is not present in the list");  
          
dList = SearchList();  
#Add nodes to the list  
dList.addNode(1);  
dList.addNode(5);  
dList.addNode(4);  
dList.addNode(2);  
dList.addNode(3);  
   
#Search for node 4 in the list  
dList.searchNode(4);  
   
#Search for node 9 in the list  
dList.searchNode(9);

 

Output:

Node is present in the list at the position : 3
Node is not present in the list

 

C

#include <stdio.h>  
#include <stdbool.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;  
   
//addNode() will add a node to the list  
void addNode(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;  
    }  
    else {  
        //newNode will be added after tail such that tail's next will point to newNode  
        tail->next = newNode;  
        //newNode's previous will point to tail  
        newNode->previous = tail;  
        //newNode will become new tail  
        tail = newNode;  
        //As it is last node, tail's next will point to NULL  
        tail->next = NULL;  
    }  
}  
   
//searchNode() will search a given node in the list  
void searchNode(int value) {  
    int i = 1;  
    bool flag = false;  
    //Node current will point to head  
    struct node *current = head;  
      
    //Checks whether the list is empty  
    if(head == NULL) {  
        printf("List is empty\n");  
        return;  
    }  
    while(current != NULL) {  
        //Compare value to be searched with each node in the list  
        if(current->data == value) {  
            flag = true;  
            break;  
        }  
        current = current->next;  
        i++;  
    }  
    if(flag)  
         printf("Node is present in the list at the position : %d\n", i);  
    else  
         printf("Node is not present in the list\n");  
}  
   
int main()  
{  
    //Add nodes to the list  
    addNode(1);  
    addNode(5);  
    addNode(4);  
    addNode(2);  
    addNode(3);  
      
    //Search for node 4 in the list  
    searchNode(4);  
    //Search for node 9 in the list  
    searchNode(9);  
   
    return 0;  
}

 

Output:

Node is present in the list at the position : 3
Node is not present in the list

 

JAVA

public class SearchList {  
      
    //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;  
      
    //addNode() will add a node to the list  
    public void addNode(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;  
        }  
        else {  
            //newNode will be added after tail such that tail's next will point to newNode  
            tail.next = newNode;  
            //newNode's previous will point to tail  
            newNode.previous = tail;  
            //newNode will become new tail  
            tail = newNode;  
            //As it is last node, tail's next will point to null  
            tail.next = null;  
        }  
    }  
      
    //searchNode() will search a given node in the list  
    public void searchNode(int value) {  
        int i = 1;  
        boolean flag = false;  
        //Node current will point to head  
        Node current = head;  
          
        //Checks whether the list is empty  
        if(head == null) {  
            System.out.println("List is empty");  
            return;  
        }  
        while(current != null) {  
            //Compare value to be searched with each node in the list  
            if(current.data == value) {  
                flag = true;  
                break;  
            }  
            current = current.next;  
            i++;  
        }  
        if(flag)  
             System.out.println("Node is present in the list at the position : " + i);  
        else  
             System.out.println("Node is not present in the list");  
    }  
      
    public static void main(String[] args) {  
          
        SearchList dList = new SearchList();  
        //Add nodes to the list  
        dList.addNode(1);  
        dList.addNode(5);  
        dList.addNode(4);  
        dList.addNode(2);  
        dList.addNode(3);  
          
        //Search for node 4 in the list  
        dList.searchNode(4);  
        //Search for node 9 in the list  
        dList.searchNode(9);  
    }  
}

 

Output:

Node is present in the list at the position : 3
Node is not present in the list

 

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 SearchList<T>{  
            //Represent the head and tail of the doubly linked list  
            protected Node<T> head = null;               
             protected Node<T> tail = null;  
              
            //addNode() will add a node to the list  
            public void addNode(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;  
                }  
                else {  
                    //newNode will be added after tail such that tail's next will point to newNode  
                    tail.next = newNode;  
                    //newNode's previous will point to tail  
                    newNode.previous = tail;  
                    //newNode will become new tail  
                    tail = newNode;  
                    //As it is last node, tail's next will point to null  
                    tail.next = null;  
                }  
            }  
              
            //searchNode() will search a given node in the list  
            public void searchNode(int value) {  
                int i = 1;  
                bool flag = false;  
                //Node current will point to head  
                Node<T> current = head;  
   
                //Checks whether the list is empty  
                if(head == null) {  
                    Console.WriteLine("List is empty");  
                    return;  
                }  
                while(current != null) {  
                    //Compare value to be searched with each node in the list  
                    if(current.data.Equals(value)) {  
                        flag = true;  
                        break;  
                    }  
                    current = current.next;  
                    i++;  
                }  
                if(flag)  
                    Console.WriteLine("Node is present in the list at the position : " + i);  
                else  
                    Console.WriteLine("Node is not present in the list");  
            }  
        }  
          
        public static void Main()  
        {  
            SearchList<int> dList = new SearchList<int>();  
            //Add nodes to the list  
            dList.addNode(1);  
            dList.addNode(5);  
            dList.addNode(4);  
            dList.addNode(2);  
            dList.addNode(3);  
   
            //Search for node 4 in the list  
            dList.searchNode(4);  
            //Search for node 9 in the list  
            dList.searchNode(9);  
        }      
    }  
}

 

Output:

Node is present in the list at the position : 3
Node is not present in the list

 

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 SearchList{  
    //Represent the head and tail of the doubly linked list  
    public $head;  
    public $tail;  
    function __construct(){  
        $this->head = NULL;  
        $this->tail = NULL;  
    }  
      
    //addNode() will add a node to the list  
    function addNode($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;  
        }  
        else {  
            //newNode will be added after tail such that tail's next will point to newNode  
            $this->tail->next = $newNode;  
            //newNode's previous will point to tail  
            $newNode->previous = $this->tail;  
            //newNode will become new tail  
            $this->tail = $newNode;  
            //As it is last node, tail's next will point to NULL  
            $this->tail->next = NULL;  
        }  
    }  
      
    //searchNode() will search a given node in the list  
    function searchNode($value) {  
        $i = 1;  
        $flag = false;  
        //Node current will point to head  
        $current = $this->head;  
          
        //Checks whether the list is empty  
        if($this->head == NULL) {  
            print("List is empty");  
            return;  
        }  
        while($current != NULL) {  
            //Compare value to be searched with each node in the list  
            if($current->data == $value) {  
                $flag = true;  
                break;  
            }  
            $current = $current->next;  
            $i++;  
        }  
        if($flag)  
             print("Node is present in the list at the position : " . $i);  
        else  
             print("Node is not present in the list");  
    }  
}  
      
$dList = new SearchList();  
//Add nodes to the list  
$dList->addNode(1);  
$dList->addNode(5);  
$dList->addNode(4);  
$dList->addNode(2);  
$dList->addNode(3);  
   
//Search for node 4 in the list  
$dList->searchNode(4);  
print("<br>");  
//Search for node 9 in the list  
$dList->searchNode(9);  
?>  
</body>  
</html>

 

Output:

Node is present in the list at the position : 3
Node is not present in the list

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Doubly Linked List Programs
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