#include <algorithm>

#include <set>

#include <iostream>

#include <stdlib.h>

#include <time.h>	// provides clock() which returns # of system clock ticks since program started.

						// also provides clock_t (the return value for the clock function)

using namespace std;



void main()

{

	multiset<clock_t>	multiple_timings;

	set<clock_t>	unique_timings;

	

	clock_t now, stop;

	

	srand(time(0));

	stop = clock() + rand()%1000;	// iterate for a random number of clock ticks < 100000

	int i;

	do

	{	multiple_timings.insert(clock());

		for (i = rand()%10; i; i--) ;	// cause a random length delay

		unique_timings.insert(clock());

		for (i = rand()%10; i; i--) ;	// cause a random length delay

		now = clock();

	} while (now < stop);

	

	if (includes(multiple_timings.begin(), multiple_timings.end(), unique_timings.begin(), unique_timings.end()))

	{	cout << "All unique timing results were also among the multiple timing results." << endl;	}

	else

	{	set<clock_t> result;

		

		set_difference(multiple_timings.begin(), multiple_timings.end(), 

							unique_timings.begin(), unique_timings.end(), inserter(result, result.begin()));

		cout << "Difference between the two sets (unique values only): " << endl;

		copy(result.begin(), result.end(), ostream_iterator<clock_t>(cout, "\t"));

	}

}