public static ArrayList<Integer> printFromToBottom (TreeNode root){
		ArrayList<Integer> list = new ArrayList<>();
		ArrayList<TreeNode> queue = new ArrayList<>();
		if (root == null) {
			return list ;
		}
		queue.add(root);
		TreeNode temp = null;
		while (!queue.isEmpty()) {
			temp = queue.remove(0);
			if (temp != null) {
				if (temp.left != null) {
					queue.add(temp.left);
				}
				if (temp.right != null) {
					queue.add(temp.right);
				}
				list.add(temp.value);
			}
		}
		return list;
	}