/**
     * Simple insertion sort.
     * @param a an array of Comparable items.
     */
    public static void insertionSort( Comparable [ ] a )
    {
        for( int p = 1; p < a.length; p++ )
        {
            Comparable tmp = a[ p ];
            int j = p;

            for( ; j > 0 && tmp.compareTo( a[ j - 1 ] ) < 0; j-- )
                a[ j ] = a[ j - 1 ];
            a[ j ] = tmp;
        }
    }