题解 | #链表的回文结构# java 比较简单的思路

import java.util.*;

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class PalindromeList {
    public boolean chkPalindrome(ListNode head) {
        if (head == null) {
            return true;
        }

        ListNode fast = head;
        ListNode slow = head;

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

        ListNode cur = slow.next;
        while (cur != null) {
            ListNode curNext = cur.next;
            cur.next = slow;
            slow = cur;
            cur = curNext;
        }

        while (slow != head) {
            if (slow.val != head.val) {
                return false;
            }
            if (head.next == slow) {
                return true;
            }
            slow = slow.next;
            head = head.next;
        }
        return true;
    }
}