//  File: quicksort.cpp
//
//  Quicksort Routines

#ifndef QUICKSORT_CPP
#define QUICKSORT_CPP

#include <iostream>
#include <cassert>

using namespace std ;

// Partition array into two parts.
// First part has items <= pivot x.
// Second part has items > pivot x. 
// The return value is the position of x.
//
template <class T>
int partition(T A[], int low, int high) {
   T x, temp ;
   int i, j ;
   
   i = low - 1;  
   j = high + 1;
   x = A[low] ;
  
   while (true) {

      // Find an element less than x 
      do {
         j = j - 1;
      } while (A[j] > x) ; 
      
      // Find an element greater than x
      do {
         i = i + 1;
      } while (A[i] < x);
                                
      // swap smaller and bigger elements, if needed
	  //
      if (i < j) {
         temp = A[j] ;
         A[j] = A[i] ;
         A[i] = temp ;
      } else {
         return j;
      }
    }
}


template <class T>
void QuickSort(T A[], int low, int high) {
   int q ;

//   cout << "QuickSort: low = " << low << ", high = " << high << endl ;

   if (low >= high) return ;
   
   q = partition(A, low, high) ;
   assert(q < high) ;

   QuickSort(A, low, q) ;
   QuickSort(A, q + 1, high) ;
}

#endif