palind list

class Solution {
    public boolean isPalindrome(ListNode head) {
        if (head == null || head.next == null) return true;

        // Step 1: Find middle using slow and fast pointers
        ListNode slow = head;
        ListNode fast = head;

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

        // Step 2: Reverse second half
        ListNode secondHalf = reverseList(slow);

        // Step 3: Compare both halves
        ListNode firstHalf = head;
        while (secondHalf != null) {
            if (firstHalf.val != secondHalf.val) {
                return false;
            }
            firstHalf = firstHalf.next;
            secondHalf = secondHalf.next;
        }

        return true;
    }

    // Helper function to reverse linked list
    private ListNode reverseList(ListNode head) {
        ListNode prev = null;
        ListNode current = head;

        while (current != null) {
            ListNode nextTemp = current.next;
            current.next = prev;
            prev = current;
            current = nextTemp;
        }

        return prev;
    }
}