import java.util.Arrays;
import java.util.Scanner;

/**
   This program measures how long it takes to sort an
   array of a user-specified size with the Shell
   sort algorithm.
*/
public class ShellSortTimer
{  
   public static void main(String[] args)
   {  
      Scanner in = new Scanner(System.in);
      System.out.print("Enter array size: ");
      int n = in.nextInt();

      // Construct random array
   
      int[] a = ArrayUtil.randomIntArray(n, 100);
      int[] a2 = Arrays.copyOf(a, a.length);
      int[] a3 = Arrays.copyOf(a, a.length);
      
      // Use stopwatch to time selection sort
      
      StopWatch timer = new StopWatch();
      
      timer.start();
      ShellSorter.sort(a);
      timer.stop();
      
      System.out.println("Elapsed time with Shell sort: " 
            + timer.getElapsedTime() + " milliseconds");

      timer.reset();
      timer.start();
      Arrays.sort(a2);
      timer.stop();

      System.out.println("Elapsed time with Arrays.sort: " 
            + timer.getElapsedTime() + " milliseconds");

      if (!Arrays.equals(a, a2)) 
      { 
         throw new IllegalStateException("Incorrect sort result"); 
      }

      timer.reset();
      timer.start();
      InsertionSorter.sort(a3);
      timer.stop();

      System.out.println("Elapsed time with insertion sort: " 
            + timer.getElapsedTime() + " milliseconds");
   }
}

   

