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 ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param head ListNode类 the head
     * @return bool布尔型
     */
    public boolean isPail (ListNode head) {
        // write code here
        ArrayList<Integer> newHead = new ArrayList<>();
        ListNode temp = fanzhuan(head, newHead);

        for (int i : newHead) {
            if (temp.val != i) {
                return false;
            }
            temp = temp.next;
        }

        return true;
    }


    public ListNode fanzhuan(ListNode head, ArrayList<Integer> newHead) {
        ListNode cur = head;
        ListNode pre = null;

        while(cur != null){
            newHead.add(cur.val);
            ListNode temp = cur.next;
            cur.next = pre;
            pre = cur;
            cur = temp;
        }
        return pre;
    }
}