public static void main(String[] args) {
        TREE<Integer> baseTree = new TREE();
        baseTree.insert(65);
        baseTree.insert(54);
        baseTree.insert(85);
        baseTree.insert(19);
        baseTree.insert(60);
        baseTree.insert(80);
        baseTree.insert(89);
        baseTree.insert(8);
        baseTree.insert(35);
        baseTree.insert(70);
        baseTree.insert(83);

        List<Integer> list = getBaseNodes(baseTree);
        for (Integer i : list) {
            System.out.println(i + " ");
        }

    }

    public static List<Integer> getBaseNodes(TREE<Integer> baseTree) {
        List<Integer> list = new ArrayList<>();
        return getBaseNodesAux(baseTree.root, 0, baseTree.height(), list);
    }

    private static List<Integer> getBaseNodesAux(Node node, int currentLevel, int height, List<Integer> list) {
        if (node == null) {
            return null;
        }

        if (height + 1 == currentLevel) {
            list.add((Integer) node.getElement());
            return list;
        }

        getBaseNodesAux(node.getRight(), (currentLevel + 1), height, list);
        getBaseNodesAux(node.getLeft(), (currentLevel + 1), height, list);
        return list;
    }