Open In App

Java Program To Check Whether The Length Of Given Linked List Is Even Or Odd

Improve
Improve
Like Article
Like
Save
Share
Report

Given a linked list, the task is to make a function which checks whether the length of the linked list is even or odd. Examples: 

Input : 1->2->3->4->NULL
Output : Even

Input : 1->2->3->4->5->NULL
Output : Odd

Method 1: Count the codes linearly 
Traverse the entire Linked List and keep counting the number of nodes. As soon as the loop is finished, we can check if the count is even or odd. You may try it yourself.
Method 2: Stepping 2 nodes at a time 
Approach:

1. Take a pointer and move that pointer two nodes at a time
2. At the end, if the pointer is NULL then length is Even, else Odd.

Java




// Java program to check length
// of a given linklist
import java.io.*;
 
class GfG{
 
// Defining structure
static class Node
{
    int data;
    Node next;
}
 
// Function to check the length
// of linklist
static int LinkedListLength(Node head)
{
    while (head != null &&
           head.next != null)
    {
        head = head.next.next;
    }
    if (head == null)
        return 0;
    return 1;
}
     
// Push function
static void push(Node head, i
                 nt info)
{
    // Allocating node
    Node node = new Node();
     
    // Info into node
    node.data = info;
     
    // Next of new node to head
    node.next = (head);
 
    // head points to new node
    (head) = node;
}
 
// Driver code
public static void main(String[] args)
{
    Node head = null;
     
    // Adding elements to Linked List
    push(head, 4);
    push(head, 5);
    push(head, 7);
    push(head, 2);
    push(head, 9);
    push(head, 6);
    push(head, 1);
    push(head, 2);
    push(head, 0);
    push(head, 5);
    push(head, 5);
    int check =
        LinkedListLength(head);
     
    // Checking for length of
    // linklist
    if(check == 0)
    {
        System.out.println("Odd");
    }
    else
    {
        System.out.println("Even");
    }
}
}
// This code is contributed by Prerna saini


Output:  

Odd

Time Complexity: O(n) 
Auxiliary Space: O(1)

Using Recursion

Java




// Java program to check length
// of a given linklist
import java.io.*;
 
class GfG{
 
// Defining structure
static class Node
{
    int data;
    Node next;
}
 
// Function to check the length
// of linklist
static int LinkedListLength(Node head)
{
    if (head == null) return 0;
    return 1+LinkedListLength(head.next);
}
     
// Push function
static void push(Node head, int info)
{
    // Allocating node
    Node node = new Node();
     
    // Info into node
    node.data = info;
     
    // Next of new node to head
    node.next = (head);
 
    // head points to new node
    (head) = node;
}
 
// Driver code
public static void main(String[] args)
{
    Node head = null;
     
    // Adding elements to Linked List
    push(head, 4);
    push(head, 5);
    push(head, 7);
    push(head, 2);
    push(head, 9);
    push(head, 6);
    push(head, 1);
    push(head, 2);
    push(head, 0);
    push(head, 5);
    push(head, 5);
    int check =
        LinkedListLength(head);
     
    // Checking for length of
    // linklist
    if(check == 0)
    {
        System.out.println("Odd");
    }
    else
    {
        System.out.println("Even");
    }
}
}
// This code is contributed by Vinay Pinjala.


Output

Odd

Time Complexity: O(n) 
Auxiliary Space: O(n)

Please refer complete article on Check whether the length of given linked list is Even or Odd for more details!



Last Updated : 24 Jan, 2023
Like Article
Save Article
Previous
Next
Share your thoughts in the comments
Similar Reads