CSC301: Tree code: Don't need the sz parameter! [44/56]

    public int size () {
        return size (root);
    }
    private static int size (Node x) {
        if (x == null) return 0;
        int sz = 0;
        sz += 1;
        sz += size (x.left);
        sz += size (x.right);
        return sz;
    }

Don't need the sz parameter!

Node x is counted postorder, as we return.

This is true regardless of where we put sz += 1, since the intermediate values are not passed around.