Solution to 'Pi Day Challenge' posted on Jonathan Boccara's blog. http://www.fluentcpp.com/2017/03/02/the-pi-day-challenge-for-expressive-code-in-c/

EstimatingPi.cpp

#include <iostream>
#include <iomanip>
#include <random>

int main(int argc, char* argv[])
{
	const double REAL_PI = 3.14159265359;

	std::random_device device;
	std::mt19937 gen(device());

	for (int n = 0; n < 10; n++)
	{
		for (int m = 0; m < 8; m++)
		{
			int number_of_points = pow(10.0, (double) m);
			int radius = pow(10.0, (double) n);

			std::uniform_real_distribution<double> dis(-radius, radius);

			int counter = 0;
			int i = 0;

			while (i < number_of_points)
			{
				double x = dis(gen);
				double y = dis(gen);

				if (hypot(x, y) <= radius) counter++;
				i++;
			}

			double pi = 4.0 * counter / (double) number_of_points;
			double error = REAL_PI - pi;

			std::cout << std::setprecision(9) << std::abs(error) << '\t';
		}
		std::cout << std::endl;
	}
	
	std::getchar();
	return EXIT_SUCCESS;
}