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Q. Program to search an element in a doubly linked listExplanationIn 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
SolutionPython#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 JAVApublic 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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