/* 
 * Program to approximate pi using Monte Carlo approach:
 * Simulate throwing darts at board with quarter-circle
 * inscribed in unit square.
 */
#include <stdio.h>
#include <stdlib.h>

double estimate_pi(int seed, int darts);

int main(void) {

	int seed;
	int darts;
	printf("enter seed, number of darts\n");
	if (scanf("%d %d", &seed, &darts) != 2) {
		printf("not numbers\n");
		return 1;
	}
	double pi = estimate_pi(seed, darts);
	printf("with %d darts approximation is %.15f\n", darts, pi);
	return 0;
}

double estimate_pi(int seed, int darts) {

	srand(seed);
	int count = 0;

	/* "throw" darts and count how many are inside the circle */
	for (int i = 0; i < darts; ++i) {
		double x = ((double) rand()) / ((double) RAND_MAX);
		double y = ((double) rand()) / ((double) RAND_MAX);
		if ((x*x + y*y) <= 1.0) {
			count += 1;
		}
	}
	return 4 * ((double) count) / ((double) darts);
}