#include <iostream>
#include <set>
#include <vector>
#include <list>
#include <chrono>
#include <thread>
#include <algorithm>

using namespace std ;

class Timer
{
  public:
   chrono::steady_clock::time_point start_time  ;
   chrono::steady_clock::time_point end_time ;
   void startTime()
      {
        start_time = chrono::steady_clock::now() ;
	  }
   void endTime()
      {
        end_time = chrono::steady_clock::now() ;
	  }
   void printTime()
      {
        chrono::milliseconds elapsed_ms =
       chrono::duration_cast<chrono::milliseconds>(end_time - start_time);

        cout << "Execution time: " << elapsed_ms.count() <<
        " milliseconds" << endl;

	  }

};

//--------------------------------------------------------


//Assume vector can only contain positive numbers
void removeDuplicates1( vector<int>& v1  )
{
  set<int> set1 ;
  int left = 0 ;
    for( int x1 : v1 )
	  {
		//not seen before
        if ( set1.count( x1 ) == 0 )
           {
              v1[left++] = x1 ;
		   }
        else
           {

		   }
		  set1.insert( x1 ) ;
	  } //for

      v1.resize( left ) ;

    cout << "v1:size: " << v1.size() << endl ;

}

void removeDuplicates2( vector<int>& v1  )
{
     int left = 1 ;
    // cout << "v1.size():" << v1.size() << endl ;
     for( int i1=1 ; i1 < v1.size() ; i1++ )
	  {
		//not seen before
		//cout << "i1: " << i1 << " " << "v1[i1]:" << v1[i1]  << endl ;
		vector<int>::iterator it =  v1.begin() ;
		vector<int>::iterator it1 =  v1.begin() + i1 ;
		int value = v1[i1]   ;
		vector<int>::iterator it2 = find( it ,  it1, value  ) ;
		//Did not find it in the left hand side of the
		//current position
		//cout << "*it2:" << *it2 << endl ;
        if (  it2    == it1   )
           {
			  // cout << "Did not find." << endl << endl ;
               v1[left++] = v1[i1] ;
		   }
	  } //for

      v1.resize( left ) ;

    cout << "v1:size: " << v1.size() << endl ;

}


int main()
{
	//Assume vector can only contain positive numbers
	vector<int> v1 ;
	int noElements = 100000 ;
	//int noElements = 2 ;
	Timer timerObject1 ;
	for( int i1=1 ; i1<=noElements ; i1++ )
	 {
        v1.push_back( i1 ) ;
        v1.push_back( i1 ) ;
	 } //for

    timerObject1.startTime() ;
    removeDuplicates1( v1 )  ;
    timerObject1.endTime() ;
    timerObject1.printTime() ;

    v1.clear() ;
	for( int i1=1 ; i1<=noElements ; i1++ )
	 {
        v1.push_back( i1 ) ;
        v1.push_back( i1 ) ;
	 } //for

    timerObject1.startTime() ;
    removeDuplicates2( v1 )  ;
    timerObject1.endTime() ;
    timerObject1.printTime() ;



    //-----------------------------------------------


    v1.clear() ;
	for( int i1=1 ; i1<=noElements ; i1++ )
	 {
        v1.push_back( i1 ) ;
	 } //for
	for( int i1=1 ; i1<=noElements ; i1++ )
	 {
        v1.push_back( i1 ) ;
	 } //for

    timerObject1.startTime() ;
    removeDuplicates1( v1 )  ;
    timerObject1.endTime() ;
    timerObject1.printTime() ;

    v1.clear() ;
	for( int i1=1 ; i1<=noElements ; i1++ )
	 {
        v1.push_back( i1 ) ;
	 } //for
	for( int i1=1 ; i1<=noElements ; i1++ )
	 {
        v1.push_back( i1 ) ;
	 } //for

    timerObject1.startTime() ;
    removeDuplicates2( v1 )  ;
    timerObject1.endTime() ;
    timerObject1.printTime() ;


    return 0;
}