モンテカルロ積分 (MCMCではない)

MC.cc

#include <bits/stdc++.h>
using namespace std;

int main() {
	int seed;
	seed = 1533627;
	srand48(seed);
	double x, y, z;
	int cnt;
	int n = 10000;
	for (int i = 0; i < n; ++i) {
		x = drand48();
		y = drand48();
		z = drand48();
		if (x*x + y*y + z*z < 1) ++cnt;
	}
	cout << 8*(double)cnt/(double)n << endl;
	return 0;
}