Check if a linked list is circular


Problem: For a given linked list, check if it is a circular linked list or not.

Problem Explanation: Circular linked list is the typical linked list in which the last Node will have it’s next point to the Head of the List. For a given linked list 10->20, 20->30, 30->10, where 10, 20 and 30 are addresses of nodes,  it is a circular linked list. Hence output is true.


Java Implementation

public class CircularLL {
    public boolean isCircular(Node node) {
        Node first = node, second = node;

        while (first != null && first.getLink() != null && second.getLink() != null && second.getLink().getLink() != null) {
            first = first.getLink();
            second = second.getLink().getLink();
            if (first.hashCode() == second.hashCode()) {
                return true;

        return false;

    public static void main(String[] args) {
        Node node1 = new Node(1, null);
        Node node2 = new Node(2, node1);
        Node node3 = new Node(3, node2);

        CircularLL circularLL = new CircularLL();

public class Node {
    private int value;
    private Node link;

    public Node(int value, Node n) {
        this.value = value; = n;

    public int getValue() {
        return value;

    public void setValue(int value) {
        this.value = value;

    public Node getLink() {
        return link;

    public void setLink(Node link) { = link;

TimeComplexity: O(n)

Note: If you find any other better way to approach to this problem or you find any issue/error in above code snippets/approaches – please share it in the comments section below and get a chance to enrol free of cost for an online Live Data Structure and Algorithm course (specially designed for interview preparation for software companies like Amazon, Google, Facebook, FlipKart, SnapDeal, HealthKart…)