OctaveFunctions/ProjectEuler/C++/Problem12.cpp

#include <iostream>
#include <cmath>
#include <chrono>

unsigned long countDivisors(unsigned long number);

int main(){
	bool found = false;
	unsigned long sum = 1;
	unsigned long counter = 2;
	const unsigned long goalDivisors = 500;

	std::chrono::high_resolution_clock::time_point startTime = std::chrono::high_resolution_clock::now();
	while(!found){
		if(countDivisors(sum) > goalDivisors){
			found = true;
		}
		else{
			sum += counter;
			++counter;
		}
	}
	std::chrono::high_resolution_clock::time_point endTime = std::chrono::high_resolution_clock::now();
	--counter;

	std::cout << "The triangular number " << sum << " is made with all number >= " << counter << " and has " << countDivisors << " divisors" << std::endl;
	std::cout << "The problem took " << std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::high_resolution_clock::duration(endTime - startTime)).count() << " milliseconds" << std::endl;

	return 0;
}

unsigned long countDivisors(unsigned long number){
	unsigned long numDivisors = 0;
	for(int cnt = 0;cnt * cnt < number;++cnt){
		//if((number % cnt) == 0){
		if(fmod((double)number, (double)cnt) == 0){
			numDivisors += 2;
		}
	}
	return numDivisors;
}