#include <stdlib.h>
#include <stdio.h>
 
 
 
/* //  quickSort
 //
 //  This public-domain C implementation by Darel R. Finley.
 //
 //  * Returns true if sort was successful, or false if the nested
 //    pivots went too deep, in which case your array will have
 //    been re-ordered, but probably not sorted correctly.
 //
 //  * This function assumes it is called with valid parameters.
 //
 //  * Example calls:
 //    quickSort(&myArray[0],5); // sorts elements 0, 1, 2, 3, and 4
 //    quickSort(&myArray[3],5); // sorts elements 3, 4, 5, 6, and 7*/

#define MAX_LEVELS 1000
   
 int quickSort(double *arr, int elements) 
 {
   double piv; 
   int    beg[MAX_LEVELS], end[MAX_LEVELS];
   int    i=0; 
   int    L, R;

   beg[0]=0; end[0]=elements;
   while (i>=0) 
   {
     L=beg[i]; R=end[i]-1;
     if (L<R) 
     {
       piv=arr[L]; 
       if (i==MAX_LEVELS-1) return -1;
       while (L<R) 
       {
         while (arr[R]>=piv && L<R) 
           R--; 
         if (L<R) 
           arr[L++]=arr[R];
         while (arr[L]<=piv && L<R) 
           L++; 
         if (L<R) 
           arr[R--]=arr[L]; 
       }
       arr[L]=piv; beg[i+1]=L+1; end[i+1]=end[i]; end[i++]=L; 
     }
     else 
     {
       i--; 
     }
   }

   return 0; 
 }