An implementation of Three-way Radix Quicksort in Swift for sorting Strings efficiently.
This is based on Section 5.1 page 719 "Three-way string quicksort" of Algorithms 4th Edition by Sedgewick and Wayne. Their Java implementation, which this is a port of, is available here: https://algs4.cs.princeton.edu/51radix/Quick3string.java.html
Wikipedia describes the algorithm here: https://en.wikipedia.org/wiki/Multi-key_quicksort