public abstract class QuickSort<T extends Comparable<T>> implements IQuickSort<T> {

 
 public T[] sort(T[] elements) {
  if(elements == null || elements.length == 0){
   return (T[]) new Comparable[0];
  }
  
  return quickSort(elements,0,elements.length-1);
 }
 
 public T[] quickSort(T[] elements, int l, int r){
  
  int i = l+1;
  int j = r;
  int p = getPivot(elements, l, r);
  
  
  
  while(i <= j){
   while(i <= j && (elements[i].compareTo(elements[p]) <= 0)){
    i = i+1;
   }
   while(i <= j && (elements[j].compareTo(elements[p])) >= 0){
    j = j-1;
   }
   
   if(i<j){
    T temp = elements[i];
    elements[i] = elements[j];
    elements[j] = temp;
   }
  }
  if(l<j){
   T temp = elements[l];
   elements[l] = elements[j];
   elements[j] = temp;
   quickSort(elements,l,j-1);
  }
  if(j<r){
   quickSort(elements,j+1,r);
  }
  return elements;
 }

}