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Program to Search an Element in a Doubly Linked List

Program to Search an Element in a Doubly Linked List on fibonacci, factorial, prime, armstrong, swap, reverse, search, sort, stack, queue, array, linkedlist, tree, graph etc.

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Q. Program to search an element in a doubly linked list

Explanation

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

Program to search an element 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".

Solution

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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