Let $A[1..n]$ be an unsorted array, we want to find the $n/lgn$ intermidiate numbers in the array.
Namely the $(n/2)+1$ biggest number and the $(n/2) + 2$ biggest number and so on... until the $(n/2) + (n/lgn)$ biggrst number.
We are studing on the select algorithm and sortings.
I think it should go somehow with select algorithm as it has an efficiency of $\Theta(n)$
But its not that simple. As just making a loop will get us to \Theta(n^2)$
Just a remainder - the select algorithm compute nad finc the median of the medians in order to find the $i$ value in the array with run tie of $\Theta(n)$