~cpp
#include <iostream>
#include <time.h>
#include <math.h>
using namespace std;
unsigned int max = 1000000;
int main()
{
double x, y;
int count = 0;
srand(time(NULL));
for(int i = 0; i < max; i++)
{
x = rand();
y = rand();
x = x/RAND_MAX;
y = y/RAND_MAX;
if(sqrt(x*x + y*y) <= 1)
// cout << x << " " << y << endl;
count++;
}
cout << 4*(double)count/max << endl;
return 0;
}