234. 回文链表

Posted 2020-11-27 duancf

请判断一个链表是否为回文链表。

示例 1:

输入: 1->2
输出: false

示例 2:

输入: 1->2->2->1
输出: true

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isPalindrome(ListNode head) {
        List<ListNode> list = new ArrayList<>();
        if(head == null)
            return true;
        while(head != null)
        {
            list.add(head);
            head = head.next;
        }
        return PalindList(list);
    }
    public boolean PalindList(List<ListNode> list)
    {
        int n = list.size();
        for(int i = 0; i < list.size() / 2; i++)
        {
            if(list.get(i).val != list.get(n - i - 1).val)
            {
                return false;
            }
        }
        return true;
    }
}