Palindrome Linked List leetcode

Given a singly linked list, determine if it is a palindrome.

Follow up:
Could you do it in O(n) time and O(1) space?

找到list的中点, 然后翻转后面的list 一一对比

public class Solution {
    public boolean isPalindrome(ListNode head) {
        if (head == null || head.next == null) {
            return true;
        }
        ListNode fast = head, slow = head;
        while (fast.next != null && fast.next.next != null) {
            fast = fast.next.next;
            slow = slow.next;
        }
        ListNode cur = reverse(slow.next);// 这里导入的是中点的下一个 因为这种找中点情况 偶数时候是在左中点, 奇数时候是在正中点
        while (cur != null) {////这里不能是head!=null 对于0->0这个list head后面还有一个元素0

            if (head.val != cur.val) {
                return false;
            }
            head = head.next;
            cur = cur.next;
        }
        return true;
    }
    public ListNode reverse(ListNode node) {
        ListNode dummy = new ListNode(0);
        dummy.next = node;
        ListNode next = node.next;
        while (next != null) {
            node.next = next.next;
            next.next = dummy.next;
            dummy.next = next;
            next = node.next;
        }
        return dummy.next;
    
    }
}