checkForPalindromeLLJava

class Solution {
    public boolean isPalindrome(ListNode head) {
                if(head==null||head.next==null)
            return true;
        ListNode slow=head;
        ListNode fast=head;
        while(fast.next!=null&&fast.next.next!=null){
            slow=slow.next;
            fast=fast.next.next;
        }
        slow.next=reverseList(slow.next);
        slow=slow.next;
        while(slow!=null){
            if(head.val!=slow.val)
                return false;
            head=head.next;
            slow=slow.next;
        }
        return true;
    }
    ListNode reverseList(ListNode head) {
        ListNode pre=null;
        ListNode next=null;
        while(head!=null){
            next=head.next;
            head.next=pre;
            pre=head;
            head=next;
        }
        return pre;
    }
}