quickselect

Hence a permutation will be less disordered after quickselect has been performed.

It is based on the quickselect algorithm and is also known as the median-of-medians algorithm.

Furthermore, the Statistics::CaseResampling module provides a function to calculate quantiles using quickselect.

Suppose, for example, that we are using quickselect (a cousin of quicksort) to select a random element of a random permutation.

Although quickselect is linear-time on average, it can require quadratic time with poor pivot choices (consider the case of pivoting around the largest element at each step).

A general selection algorithm that is efficient in practice, but has poor worst-case performance, was conceived by the inventor of quicksort, C.A.R. Hoare, and is known as Hoare's selection algorithm or quickselect.