Quickselect (also known as Hoare's selection algorithm) is a selection
algorithm to find the kth smallest (or largest) element in an unordered list of
n elements.
Quicksort is a divide-and-conquer algorithm. It works by selecting a 'pivot'
element from the array and partitioning the other elements into two sub-arrays,
according to whether they are less than or greater than the pivot. The
sub-arrays are then sorted recursively.