Palindrome Linked List

234. Palindrome Linked List
Given the head of a singly linked list, return true if it is a palindrome or false otherwise.

Example 1:
Input: head = [1,2,2,1]
Output: true

Example 2:
Input: head = [1,2]
Output: false


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

        ListNode mid = middleList(head);
        ListNode secondHalf = reverse(mid.next);
        ListNode firstHalf = head;
        while(secondHalf != null){
            if(firstHalf.val != secondHalf.val){
                return false;
            }
            firstHalf = firstHalf.next;
            secondHalf = secondHalf.next;
        }
        return true;
    }
    public ListNode middleList(ListNode head){
        ListNode hare = head;
        ListNode turtle = head;
        while(hare.next != null && hare.next.next != null){
            hare = hare.next.next;
            turtle = turtle.next;
        }
        return turtle;
    }

    public ListNode reverse(ListNode head){
        ListNode prev = null;
        ListNode curr = head;
        while(curr != null){
            ListNode next = curr.next;
            curr.next = prev;
            prev = curr;
            curr = next;
        }
        return prev;
    }
}