//				 QUICKSORT

void swap ( int* ia, int i, int j )
{ // swap two elements of an array
     int tmp = ia[ i ];
     ia[ i ] = ia[ j ];
     ia[ j ] = tmp;
}

void qsort( int* ia, int low, int high )
{ // quick sort
  // stopping condition for recursion
     if ( low < high ) {
	  int lo = low;
	  int hi = high + 1;
	  int elem = ia[ low ];
			
          for (;;) {
	      while ( ia[ ++lo ] < elem ) ;
	      while ( ia[ --hi ] > elem ) ;
				
	      if ( lo < hi )
		 swap( ia, lo, hi );
	      else break;
	   }  // end, for(;;)

	swap( ia, low, hi );

	// Recursive calls:
	qsort( ia, low, hi - 1 );
	qsort( ia, hi + 1, high );
	} // end, if ( low < high )
}