Method findMidNode

12_LinkedList.java/LL.java:176–187

(Node head)

    }

    private Node findMidNode(Node head) {
        Node slow = head;
        Node fast = head.next;
        //important because we want final mid to be end of 1st half in even case, 
        //not start of 2nd half. Because mid.next is start of 2nd half.

        while(fast!= null && fast.next!=null) {
            slow = slow.next;
            fast = fast.next.next;
        }
        return slow;
    }

    public boolean checkPalindrome() {
        if(head == null || head.next == null) {