static boolean hasCycle(SinglyLinkedListNode head) { if (head == null || head.next == null) { return false; } SinglyLinkedListNode slow = head; SinglyLinkedListNode fast = head.next; while (fast != null && fast.next != null) { if (slow == fast) { return true; } slow = slow.next; fast = fast.next.next; } return false; }