剑指offer第三题 从尾到头打印链表

 1 /**
 2 *    public class ListNode {
 3 *        int val;
 4 *        ListNode next = null;
 5 *
 6 *        ListNode(int val) {
 7 *            this.val = val;
 8 *        }
 9 *    }
10 *
11 */
12 import java.util.*;
13 public class Solution {
14     public ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
15         if(listNode == null){
16             return new ArrayList();
17         }else{
18             ArrayList<Integer> arr = new ArrayList<Integer>();
19             Stack<Integer> ss = new Stack<Integer>();
20             while(listNode!=null){
21                 ss.push(Integer.valueOf(listNode.val));
22                 listNode = listNode.next;
23             }
24             while(!ss.empty()){
25                 arr.add(ss.pop());
26             }
27             return arr;
28         }
29     }
30 }