private void sumNumbersRec(TreeNode root, int tmp) {
		if(root == null) return;
		if(root.left == null && root.right == null){
			this.res += tmp + root.val;
		}
		if(root.left != null){
			sumNumbersRec(root.left, (tmp + root.val) * 10);
		}
		if(root.right != null){
			sumNumbersRec(root.right, (tmp + root.val) * 10);
		}
    }