private static int strangeCount2(TreeNode node) {
        if (node == null || isLeaf(node)){
            return 0;
        } else if (node.left == null){
            return 1 + strangeCount2(node.right);
        } else if (node.right == null){
            return 1+ strangeCount2(node.left);
        } else {
            return strangeCount2(node.left)+strangeCount2(node.right);
        }
    }

    private static boolean isLeaf(TreeNode n) {
        return (n == null) ? false : (n.left == null && n.right == null);
    }