Asymptotic bound of a heap's height
Yes $\Theta(logn)$ is correct. By the definition of $\Theta$ notation we can say that some function $g(n)$ is at least $k_1⋅f(n)$ and also it is at most $k_2⋅f(n)$ for considerably large $n$ and $k_1 &gt; 0$ and $k_2 &gt; 0$. If you apply this definition to the heap's height, you will find that the heap's height satisfies this. So, $\Theta(logn)$ is totally correct.