import java.util.*;

class QuickSort2
// Constructive quick sort on a random ArrayList of integers
// Timed but not printed
{
 public static void main(String[] args) throws Exception
 {
  Random rand = new Random();
  long time1,time2;
  Scanner input = new Scanner(System.in);
  System.out.print("Enter the number of numbers: ");
  int num = input.nextInt();
  System.out.print("Enter the highest number: ");
  int high = input.nextInt();
  ArrayList<Integer> a = new ArrayList<Integer>();
  for(int i=0; i<num; i++)
      a.add(rand.nextInt(high));
  time1 = new Date().getTime();
  ArrayList<Integer> b=sort(a);
  time2 = new Date().getTime();
  System.out.println("Time taken to sort: "+(time2-time1)+"ms");
 }

 public static ArrayList<Integer> sort(ArrayList<Integer> a)
 {
  if(a.size()<=0)
     return a;
  ArrayList<Integer> smaller = new ArrayList<Integer>();
  ArrayList<Integer> greater = new ArrayList<Integer>();
  Integer pivot = a.get(0);
  for(int i=1; i<a.size(); i++)
     {
      Integer n=a.get(i);
      if(n.compareTo(pivot)<0)
         smaller.add(n);
      else
         greater.add(n);
     }
  smaller=sort(smaller);
  greater=sort(greater);
  smaller.add(pivot);
  smaller.addAll(greater);
  return smaller;
 }

}