Node findCycle() {
        Node tortoise = this.next;
        Node hare = this.next.next;
        while(tortoise != hare) {
            tortoise = tortoise.next;
            hare = hare.next.next;
        }
        
        tortoise = this;
        while(tortoise != hare) {
            tortoise = tortoise.next;
            hare = hare.next;
        }
        
        return tortoise;
    }