JavaScript Program to Print Odd Numbers in a Linked List

This article will show you different ways to find and print all the odd numbers in a linked list using JavaScript.

Example:

Input: 2->1->9->3
Output: 1, 9, 3
Input: 5->5->1->0->19->8
Output: 5, 5, 1, 19

Using Recursive Approach

This recursive method checks each node in the linked list to determine if the current node’s data represents an odd number, and if so, it is printed.

Example: This example shows the use of the above-explained approach.

Javascript

// JavaScript program to print odd numbers
// in a linked list using recursive approach

// Node class represents each element in
// the linked list
class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }
}

// LinkedList class manages the
// linked list operations
class LinkedList {
  constructor() {
    this.head = null;
  }

  // Method to add a new node at the
   //beginning of the linked list
  addNode(data) {
    let newNode = new Node(data);
    newNode.next = this.head;
    this.head = newNode;
  }

  // Recursive method to print
  // odd numbers in the linked list
  oddNumbers(current) {
    // Base case: if current node is null, return
    if (current === null) {
      return;
    }

    // Check if the data of the current node
    // is odd, and print if true
    if (current.data % 2 !== 0) {
      console.log(current.data);
    }

    // Recursive call for the next node in the linked list
    this.oddNumbers(current.next);
  }
}

// Example
let linkedList = new LinkedList();
linkedList.addNode(1);
linkedList.addNode(4);
linkedList.addNode(7);
linkedList.addNode(9);
linkedList.addNode(2);

// Displaying odd numbers in the linked list
// using the recursive approach
console.log(
    "Odd numbers in the linked list using recursive approach:");
linkedList.oddNumbers(linkedList.head);

Output

Odd numbers in the linked list using recursive approach:
9
7
1

Time Complexity: O(n)

Space Complexity: O(n)

Using While Loop

To print odd numbers in a linked list with the while loop method, we go through each node step by step until we reach the end of the list. At each node, we check whether the node’s data is odd, and if so, we display it.

Example: This example shows the use of the above-explained approach.

Javascript

// JavaScript program to print
// odd numbers in a linked list using while loop

// Node class represents each element in the linked list
class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }
}

// LinkedList class manages the linked list operations
class LinkedList {
  constructor() {
    this.head = null;
  }

  // Method to add a new node at the
  // beginning of the linked list
  addNode(data) {
    let newNode = new Node(data);
    newNode.next = this.head;
    this.head = newNode;
  }

  // Method to print odd numbers in the
  // linked list using while loop
  oddNumbers() {
    let current = this.head;

    // While loop to iterate through the linked list
    while (current !== null) {
      // Check if the data of the current
      // node is odd, and print if true
      if (current.data % 2 !== 0) {
        console.log(current.data);
      }
      current = current.next;
    }
  }
}

// Example
let linkedList = new LinkedList();
linkedList.addNode(2);
linkedList.addNode(11);
linkedList.addNode(4);
linkedList.addNode(8);
linkedList.addNode(9);

// Displaying odd numbers in the linked list
// using the while loop approach
console.log("Odd numbers in the linked list:");
linkedList.oddNumbers();

Output

Odd numbers in the linked list:
9
11

Time Complexity: O(n)

Space Complexity: O(1)

Using For Loop

This method uses the same approach as above, but with the use of a ‘for loop’ instead of a ‘while loop’.

Example: This example shows the use of the above-explained approach.

Javascript

// JavaScript program to print odd numbers
// in a linked list using for loop

// Node class represents each element in the linked list
class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }
}

// LinkedList class manages the linked list operations
class LinkedList {
  constructor() {
    this.head = null;
  }

  // Method to add a new node at the beginning
  // of the linked list
  addNode(data) {
    let newNode = new Node(data);
    newNode.next = this.head;
    this.head = newNode;
  }

  // Method to print odd numbers in the
  // linked list using for loop
  printOddNumbers() {
    // For loop to iterate through the linked list
    for (let current = this.head; current !== null; current = current.next) {
      // Check if the data of the current node is odd, and print if true
      if (current.data % 2 !== 0) {
        console.log(current.data);
      }
    }
  }
}

// Example
let linkedList = new LinkedList();
linkedList.addNode(1);
linkedList.addNode(9);
linkedList.addNode(3);
linkedList.addNode(4);
linkedList.addNode(7);

// Displaying odd numbers in the linked list
// using the for loop approach
console.log("Odd numbers in the linked list:");
linkedList.printOddNumbers();

Output

Odd numbers in the linked list:
7
3
9
1

Time Complexity: O(n)

Space Complexity: O(1)