insert_sorted

public Node insertData(Node llist, int data){
    // Write your code here
    Node curr = llist;
    Node node = new Node(data);

    if (llist == null) return node;
    else if(node.data < curr.data){
        // insert in the beginning
        node.next = curr;
        curr.prev = node;
        return node;
    }else{
        // node = 3         curr = 1, 2, 4;
        //
        while(curr != null) {
            if (curr.next == null  || curr.next.data >= data){
                node.next = curr.next;
                node.prev = curr;
                if (curr.next != null){
                    curr.next.prev = node;
                }
                curr.next = node;
                break;
            }
            curr = curr.next;
        }
    }

    return curr;
}