给一个二叉树，依次从上到下返回最右边数值

public static List<Integer> rightSideView(TreeNode root) {
        ArrayList<TreeNode> list = new ArrayList<TreeNode>();
        ArrayList<Integer> resultList = new ArrayList<Integer>();
        if (root == null) {
            return resultList;
        }
        list.add(root);
        addRightSideNode(list, resultList);
        return resultList;
    }
    
    public static void addRightSideNode(ArrayList<TreeNode> list,ArrayList<Integer> resultList) {
        if (list !=null &&list.size() == 0) {
            return;
        }
        resultList.add(list.get(list.size() - 1).val);
        ArrayList<TreeNode> newList = new ArrayList<TreeNode>();
        for (TreeNode node : list) {
            if (node.left != null) {
                newList.add(node.left);
            }
            if (node.right != null) {
                newList.add(node.right);
            }
        }
        addRightSideNode(newList, resultList);
    }