path: root/src/algorithms/shuffling/KnuthShuffle.java

/**
 * Copyright © 2014  Mattias Andrée (m@maandree.se)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package algorithms.shuffling;

import java.util.Random;


/**
 * Bias free array shuffling class using Knuth Shuffle.<br>
 * Sattolo Cycle is an improvement of this method.
 */
public class KnuthShuffle
{
£>for T in boolean char byte short int long float double Object; do
    /**
     * Shuffles an array
     *
     * @param  array   The array to shuffle
     * @param  random  The random generator to use
     */
    public static void shuffle(£{T}[] array, Random random)
    {
        int i = 0, j;
        int n = array.length - 1;
        for (;;)
	{
	    if (i == n)
		break;
            
	    £{T} temp = array[i];
	    array[i] = array[j = random.nextInt(n - i) + i + 1];
	    array[j] = temp;
            
	    i++;
	}
    }
£>done
}