palindromeLL

   public boolean isPalindrome(ListNode head) {

        ListNode slow = head;
        ListNode fast = head;

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

        slow = reverseList(slow);    // reverse half
        ListNode newHead = head;

        while(slow!=null){
            if(slow.val!=newHead.val){   // check half and half
                return false;
            }
            slow= slow.next;
            newHead=newHead.next;
        }
        return true;
    }

   public ListNode reverseList(ListNode head) {
        ListNode prev = null;
        ListNode next = null;
        ListNode curr = head;
        while(curr!=null){
            next=curr.next;
            curr.next=prev;
            prev=curr;
            curr=next;

        }
        return prev;

    }
}