Decide whether the series are absolutely convergent, conditionally convergent, or divergent.
$$a) \sum _{n=1}^{\infty} (-1)^n \frac{(\log n)^{\log n}}{n^a} , a>0$$
$$b) \sum_{n=1}^{\infty} \frac {(-1)^{[\log n]}}{n}$$ where [ ] is greatest integer symbol.
My attempt : the easiest way to think about this problem is the Leibniz test both $a)$ and $b)$ will be conditionally convergents.
Is it correct ?
any hints/solutions
thanks u