Question 2

class Finder {
    public static Node getCycleStart(Node start) {
        ///Floyd's cycle detection algorithm
        Node fast = start;
        Node slow = start;

        while (fast.next != null) {
            slow = slow.next;
            fast = fast.next.next;
            if (slow == fast) {
                break;
            }
        }

        if (fast.next == null) {
            return null;
        }

        slow = start;
        while (slow != fast) {
            slow = slow.next;
            fast = fast.next;
        }

        return fast;
    }
}