NC96 判断一个链表是否为回文结构

NC96 判断一个链表是否为回文结构

判断一个链表是否为回文结构_牛客题霸_牛客网 (nowcoder.com)

import java.util.*;
public class Solution {
    public ListNode reverse(ListNode head){
        ListNode prev=null;
        ListNode cur=head;
        while(cur!=null){
            ListNode next=cur.next;
            cur.next=prev;
            prev=cur;
            cur=next;
        }
        return prev;
    }
    public boolean isPail (ListNode head) {
        if(head==null){
            return true;
        }
        ListNode slow=head;
        ListNode fast=head;
        while(fast!=null&&fast.next!=null){
            slow=slow.next;
            fast=fast.next.next;
        }
        slow=reverse(slow);
        while(slow!=null){
            if(slow.val!=head.val){
                return false;
            }
            slow=slow.next;
            head=head.next;
        }
        return true;
    }
}