> Ok, I looked at it closer and I admit that quicksort implemented in C won't take days on an input of 2³¹ elements. It will take less than 1-2 hours, I think.

> Ok, I looked at it closer and I admit that quicksort implemented in C won't take days on an input of 2³¹ elements. It will take less than 1-2 hours, I think. How ancient is your machine? Quicksorting (2^31 - 16) elements (because that's Java's hardcoded limit) takes < 11 seconds on my machine, and a big chunk of that time is taken in the random number generation to create the input... # Temp.java import java.util.*; public class Temp { public static void main(String[] args) { byte[] arr = new byte[0x7FFFFFF0]; new Random().nextBytes(arr); Arrays.sort(arr); } } $ javac Temp.java && time -p java Temp real 10.30