#include <cmath>
#include <iostream>
#include <iomanip>
double calcPi(double precision){
double PI = 1.0, temp;
for(double i = 0.0; i < precision; i++){
temp = 1.0;
temp /= (3 + i * 2) * pow(3, i + 1);
PI += (int(i) % 2 == 0)? -temp : temp;
}
return sqrt(12) * PI;
}
int main() {
std::cout << std::setprecision(500) << calcPi(50000) << std::endl;
return 0;
}
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