public static void myQuick(int[] tab, int left, int right)
        {
            int s = (left + right) / 2;
            int pivot = tab[s];
            swap(tab, s, right);
            int b = left;
            for(int a=left;a<right;a++)
            {
                if(tab[a]<=pivot)
                {
                    swap(tab, a, b);
                    b++;
                }
            }
            swap(tab, b, right);
            myQuick(tab, left, b - 1);
            myQuick(tab, b + 1, right);
            }