shuffler

//------------------------------ Assignment -----------------------------------
//  	Programmer:Junnun Ali    	     	     Course-Section:AP comp sci
//  	E-mail address:                              Assignment: activity 3
//	Creation Date:                               Last Modified: 3/2/15
//-----------------------------------------------------------------------------
//	PURPOSE:
//-----------------------------------------------------------------------------
//	INPUT:
//-----------------------------------------------------------------------------
//	OUTPUT:
//-----------------------------------------------------------------------------
//	NOTES: 1. No error checking is done on the information provided by user.
//-----------------------------------------------------------------------------

/**
 * This class provides a convenient way to test shuffling methods.
 */
public class Shuffler {


	  //The number of consecutive shuffle steps to be performed in each call to each sorting procedure.

	private static final int SHUFFLE_COUNT = 5;

	private static final int VALUE_COUNT = 4;


	public static void main(String[] args) {
		System.out.println("Results of " + SHUFFLE_COUNT +
								 " consecutive perfect shuffles:");
		int[] values1 = new int[VALUE_COUNT];
		for (int i = 0; i < values1.length; i++) {
			values1[i] = i;
			}
		for (int j = 1; j <= SHUFFLE_COUNT; j++) {
			perfectShuffle(values1);
			System.out.print("  " + j + ":");
			for (int k = 0; k < values1.length; k++) {
				System.out.print(" " + values1[k]);
			}
			System.out.println();
		}
		System.out.println();

		System.out.println("Results of " + SHUFFLE_COUNT +
								 " consecutive efficient selection shuffles:");
		int[] values2 = new int[VALUE_COUNT];
		for (int i = 0; i < values2.length; i++) {
			values2[i] = i;
			}
		for (int j = 1; j <= SHUFFLE_COUNT; j++) {
			selectionShuffle(values2);
			System.out.print("  " + j + ":");
			for (int k = 0; k < values2.length; k++) {
				System.out.print(" " + values2[k]);
			}
			System.out.println();
		}
		System.out.println();
	}



	public static void perfectShuffle(int[] values) {
		int[] temp = new int[values.length];
		int mid = (values.length + 1) / 2;

		// Interleave elements 0 ... mid-1 with elements mid ... length-1
		int unshuffledPos = 0;
		int k = 0;
		for ( ; k < mid; k++) {
			temp[unshuffledPos] = values[k];
			unshuffledPos += 2;
		}
		unshuffledPos = 1;
		for ( ; k < values.length; k++) {
			temp[unshuffledPos] = values[k];
			unshuffledPos += 2;
		}

		// Copy elements back to values
		for (k = 0; k < values.length; k++) {
			values[k] = temp[k];
		}
	}



	public static void selectionShuffle(int[] values) {
		for (int k = values.length - 1; k > 0; k--) {
			int pos = (int) (Math.random() * (k + 1));  // range 0 to k, inclusive
			int temp = values[pos];
			values[pos] = values[k];
			values[k] = temp;
		}
	}
}