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 ListNode slow = head, fast = head; while(fast != null && fast.next != null){ slow = slow.next; fast = fast.next.next; } ListNode reverseList = reverse(slow); ListNode cur1 = reverseList, cur2 = head; while(cur1 != null){ if(cur1.val != cur2.val){ return false; } cur1 = cur1.next; cur2 = cur2.next; } return true; }

public ListNode reverse(ListNode head){
    ListNode cur = head, pre = null;
    while(cur != null){
        ListNode tmp = cur.next;
        cur.next = pre;
        pre = cur;
        cur = tmp;
    }
    return pre;
}

}