题解 | #判断一个链表是否为回文结构#

import java.util.*;

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

public class Solution {
    /**
     * 
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    public boolean isPail (ListNode head) {
        // write code here
        if(head == null || head.next == null) {
            return true;
        }
        LinkedList<Integer> nums = new LinkedList<>();
        ListNode p = head;
        while(p != null) {
            nums.addLast(p.val);
            p = p.next;
        }
        while(nums.size() > 1 && (int)nums.getFirst() == (int)nums.getLast()) {
            nums.removeFirst();
            nums.removeLast();
        }
        System.out.println(nums.size());
        return nums.size() <= 1;
    }
}