import java.util.Arrays;

public class QuickSortClean
{
    /* -------------------------------------------------------
       QuickSort: A[s.. e-1]
        ------------------------------------------------------ */
    public static <T extends Comparable<T>> void sort(T[] A, int s, int e)
    {
	if ( e - s <= 1 )	// Base case
	    return;		// No need to sort an array of 1 element...

	// Partition A using A[s] as pivot
	int pivotLoc = partition(A, s, e);

	sort(A, s, pivotLoc);	// Sort left  half with quick sort
	sort(A, pivotLoc+1, e);	// Sort right half with quick sort
    }



    /* --------------------------------------------------------
       Input:  A[lo] .... A[hi-1]
                 ^
		 |
	       pivot

       Output: Partition A[s] ... A[e-1] so that:
	       pivot = A[s]

               |  values < pivot     | A[s] | values > A[lo] |
                                         ^
					 |
				      index k
       Returns: k
       --------------------------------------------------------- */
    public static <T extends Comparable<T>> int partition(T[] A, int s, int e) 
    {
	T pivot = A[s];
	
        int low = s+1, high = e-1;

        while (low <= high) 
        {
	    if ( A[high].compareTo(pivot) >= 0 )
            {
		high--;
            }
	    else
	    {
		exch(A, low, high);
		low++;
	    }

        }

	exch(A, s, high);

	return high;
    }

    public static <T extends Comparable<T>> void exch(T[] A, int i, int j)
    {
        T h = A[i];
	A[i] = A[j];
	A[j] = h;
    }
}