clrs; exercise 9.3.5 - black-box linear selection algorithm
clrs; exercise 9.3.6 - k-th quantiles
clrs; exercise 9.3.7 - the s elements, closest to the median
clrs; exercise 9.3.8 - median of 2 sorted arrays (equal in length)
clrs; exercise 9.3.9 - Professor Olay and his pipeline