public static DoublyLinkedListNode sortedInsert(DoublyLinkedListNode llist, int data) {
        //if llist is null, set it to a new node w/ data
        if(llist == null) return llist = new DoublyLinkedListNode(data);
        
        //init a new node w/ data
        DoublyLinkedListNode newNode = new DoublyLinkedListNode(data);
        DoublyLinkedListNode curr = llist;
        
        //if the first node's data is >= than new node's data
        if(data <= llist.data){
            newNode.next = llist;
            llist.prev = newNode;
            return newNode;
        }
        
        //iterate thru llist
        while(curr != null){
            //if curr data is <= curr and next data is > curr or null, insert new node
            if(curr.data <= data && (curr.next == null || curr.next.data > data)){
                newNode.next = curr.next;
                newNode.prev = curr;
                if(curr.next != null) curr.next.prev = newNode;
                curr.next = newNode;
                break;
            }
            curr = curr.next;
        }
        //return llist
        return llist;
    }