**********Median********************************************
public static int median(Vector a, int lo, int hi) {
    	// TODO
    	int median=(lo+hi)/2;
    	System.out.println("la mediane est :"+a.get(median));
        return a.get(median);
    }



    private static boolean less(int v, int w)
    {
    	return v<w;
    }

    public static void sort(Vector a)
    {
    	// Sort a[] into increasing order.
	    int N = a.size(); // array length
	    for (int i = 0; i < N; i++)
	    {
	    	// Exchange a[i] with smallest entry in a[i+1...N).
		    int min = i;
		    for (int j = i+1; j < N; j++)
		    if (less(a.get(j), a.get(min))) min = j;
		    a.swap(i, min);
	    }

	    for (int i = 0; i < N; i++)
	    {
	    	//a.set(i, i*5);
	    	System.out.println(a.get(i));
	    }


	 }


    public static void initializ(Vector a)
    {
    	int N = a.size();
    	int j=50;
	    for (int i = 0; i < N; i++)
	    {

	    	a.set(i, j);
	    	j=j-5;

	    }
	 }
**********************************************************************************************
********** merge sort ********************************************************************
public class MergeSort {
    /**
     * Pre-conditions: a[lo..mid] and a[mid+1..hi] are sorted
     * Post-conditions: a[lo..hi] is sorted
     */
    private static void merge(Comparable[] a, Comparable[] aux, int lo, int mid, int hi) {
        for (int k = lo; k <= hi; k++) {
            aux[k] = a[k];
        }

        int i = lo;
        int j = mid + 1;
        for (int k = lo; k <= hi; k++) {
            if (i > mid) {
                a[k] = aux[j++];
            } else if (j > hi) {
                a[k] = aux[i++];
            } else if (aux[j].compareTo(aux[i]) < 0) {
                a[k] = aux[j++];
            } else {
                a[k] = aux[i++];
            }
        }
    }

    // Mergesort a[lo..hi] using auxiliary array aux[lo..hi]
    private static void sort(Comparable[] a, Comparable[] aux, int lo, int hi) {
        // TODO
    }

    /**
     * Rearranges the array in ascending order, using the natural order
     */
    public static void sort(Comparable[] a) {
        // TODO
    }
}