Recursive Quicksort C++ Implementation

recursive_quicksort.cpp

//============================================================================
// Name        : QuickSort.cpp
// Author      : Talisson Bento
// Version     :
// Copyright   : Your copyright notice
// Description : Sort in C++, Ansi-style
//============================================================================

#include <iostream>
#include <vector>
#include <algorithm>
#include <chrono>

using namespace std;


class Timer
{
public:
  Timer()
  {
    this->reset();
  }
  void reset()
  {
     this->start_ = std::chrono::high_resolution_clock::now();
  }

  long elapsed()
  {
     return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::high_resolution_clock::now() - this->start_).count();
  }

private:
  std::chrono::steady_clock::time_point start_;

};

template<class Iterator>
Iterator partition(Iterator start, Iterator end)
{

  Iterator middle = start + static_cast<int>(std::distance(start, end) / 2);
  std::iter_swap(start, middle);

  Iterator pivot = start;
  Iterator left = std::next(start);

  while(start != end)
    {
      if(*start < *pivot)
	{
	  std::iter_swap(left, start);
	  ++left;
	}

      ++start;
    }

  std::advance(left, -1);
  std::iter_swap(left, pivot);
  return left;

}

template<class Iterator>
void recursive_quicksort(Iterator start, Iterator end)
{

  if(std::distance(start, end) > 1)
    {
	Iterator pivot = partition(start, end);
	recursive_quicksort(start, pivot);
	recursive_quicksort(pivot, end);
    }
}

int main()
{
  Timer timer;
  std::srand(0);

  vector<int> container(1000000);
  std::generate(container.begin(), container.end(), std::rand);

  timer.reset();
  recursive_quicksort(container.begin(), container.end());
  std::cout << "sort "<< container.size() <<  " items in " << timer.elapsed() <<  " ms" << std::endl;
  /*int i =1;
  for(auto& it : container)
    {
      //cout << "#" << i++ << "\t" << it << endl;
    }*/

  return 0;
}