从尾到头打印链表

https://www.nowcoder.com/practice/d0267f7f55b3412ba93bd35cfa8e8035
思路：遍历链表将每个节点的值存入数组中，然后将数组反转返回。
学习一下如何定义链表！

public class print_linked_list_from_end_to_end {
    public static class ListNode {
        int val;
        ListNode next = null;
        ListNode(int val) {
            this.val = val;
        }
    }
    public static void main(String[] args) {
        ListNode node1 = new ListNode(1);
        ListNode node2 = new ListNode(2);
        ListNode node3 = new ListNode(3);
        node1.next = node2;
        node2.next = node3;
        ArrayList arrayList = printListFromTailToHead(node1);
        System.out.println(arrayList);
    }
    public static ArrayList<Integer> printListFromTailToHead(ListNode listNode) {
        ArrayList arrayList = new ArrayList();
        while (listNode != null) {
            arrayList.add(listNode.val);
            listNode = listNode.next;
        }
        Collections.reverse(arrayList);
        return arrayList;
    }
}