题解 | #判断一个链表是否为回文结构#

/*
 * 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) {
        if(head==null) return true;
        // write code here
        //反转链表数据进栈
        Stack<Integer> st =new Stack<>();
        st=reverse(head);
        ListNode temp=head;
        while(temp!=null){
            int num=st.pop();
            if(temp.val!=num){
                return false;
            }
            temp=temp.next;
        }
        return true;
    }
    public Stack<Integer> reverse(ListNode head){
        Stack<Integer> st = new Stack<Integer>();
        ListNode tempNode=head;
        while(tempNode!=null){
            st.push(tempNode.val);
            tempNode=tempNode.next;
        }
        return st;
        }
}