/**
 * Class to hold quicksort.
 */
public class QuickSort {

    /**
     * Sorts array (in ascending order).
     */
    public static <T extends Comparable> void sort(T[] data) {
        qsort(data, 0, data.length-1);
    }

    /**
     * Tests whether array is sorted.
     */
    public static <T extends Comparable> boolean isSorted(T[] data) {
        for (int i = 0; i < data.length-1; ++i) {
            if (data[i].compareTo(data[i+1]) > 0)
                return false;
        }
        return true;
    }

    /**
     * Sorts array from startIndex through endIndex.
     */
    private static <T extends Comparable> void qsort(T[] data, 
            int startIndex, int endIndex) {
        // YOUR CODE GOES HERE
    }
}