import java.util.Random;

/**
 * This class contains utility methods for array manipulation.
 */
public class ArrayUtil
{
    private static Random generator = new Random();

    /**
     * Creates an array filled with random values.
     * @param length the length of the array
     * @param n the number of possible random values
     * @return an array filled with length numbers between 0 and n - 1
     */
    public static int[] randomIntArray(int length, int n)
    {
        int[] a = new int[length];
        for (int i = 0; i < a.length; i++) {
            a[i] = generator.nextInt(n);
        }

        return a;
    }

    /**
     * Swaps two entries of an array.
     * @param a the array
     * @param i the first position to swap
     * @param j the second position to swap
     */
    public static void swap(int[] a, int i, int j)
    {
        int temp = a[i];
        a[i] = a[j];
        a[j] = temp;
    }
}