Method isCycleExists

Java/linked-list-cycle-ii.java:34–49

(ListNode head)

    }
    
    public ListNode isCycleExists(ListNode head){
        ListNode currentHead = head;
        
        ListNode slowPtr = head;
        ListNode fastPtr = head;
        
        while (fastPtr != null && fastPtr.next != null) {
            slowPtr = slowPtr.next;
            fastPtr = fastPtr.next.next;

            if (slowPtr == fastPtr)
                return slowPtr;
        }
        
        return null;
    }
    
}