/**

 * Definition for singly-linked list.

 * public class ListNode {

 *     int val;

 *     ListNode next;

 *     ListNode() {}

 *     ListNode(int val) { this.val = val; }

 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }

 * }

 */

class Solution {

    public static ListNode reverseLL(ListNode head) {

        ListNode cur = head;

        ListNode prev = null;

        ListNode next = null;

        while (cur != null) {

            next = cur.next;

            cur.next = prev;

            prev = cur;

            cur = next;

        }

        return prev;

    }

    public static ListNode midPointLL (ListNode head)  {

        ListNode slow = head;

        ListNode fast = head;

        while (fast.next != null && fast.next.next != null) {

            slow = slow.next;

            fast = fast.next.next;

        }

        return slow;

    }

    public boolean isPalindrome(ListNode head) {

        ListNode midNode = midPointLL(head);

        ListNode temp = midNode.next;

        midNode.next = null;

        ListNode newHead = reverseLL(temp);

        ListNode t1 = head;

        ListNode t2 = newHead;

        while (t1 != null && t2 != null) {

            if (t1.val != t2.val)

                return false;

            t1 = t1.next;

            t2 = t2.next;

        }

        return true;

    }

}