Method mergeSortHelper

12_LinkedList.java/LL.java:257–273

(Node head)

    }
    
    private Node mergeSortHelper(Node head) {
        if(head == null || head.next == null) {
            return head;
        }

        
        Node mid = findMidNode(head);
        //System.out.println(mid.data);
        Node head2 = mid.next;
        mid.next = null;
        Node newHead1 = mergeSortHelper(head);
        Node newHead2 = mergeSortHelper(head2);
       // System.out.println(newHead1.data+" "+newHead2.data);
        Node finalHead = merge(newHead1, newHead2);

        return finalHead;
    }

    private Node merge(Node head1, Node head2) {
        Node finalHead = new Node(-1);