Make Quicksort as fast as you can.

Your program is to generate a large number (supplied by the user) of random
strings, and sort them using quicksort. It must time itself performing the
sort, and report to the user how long it took.

Your program must also verify its own correctness:
+ After generating the array of random strings, make a copy of it.
+ After timing your own sort of the array, use the standard library qsort
  function to sort the copy of the array
+ Compare the two arrays to make sure your sort produced the same results
  as qsort

Here is the special timing function

#include <time.h>
#include <sys/resource.h>

double get_cpu_time()
{ struct rusage ruse;
  getrusage(RUSAGE_SELF, &ruse);
  return ruse.ru_utime.tv_sec+ruse.ru_utime.tv_usec/1000000.0 + 
         ruse.ru_stime.tv_sec+ruse.ru_stime.tv_usec/1000000.0; }