import std.stdio;
import std.datetime.stopwatch;
import std.math:pow;

const int ITERATIONS = 1_000_000;
const int BENCHMARKS = 20;

double leibniz(int iter) {
  double n = 1.0;
  for (int i = 2; i <= iter - 1; i++) {
    n += pow(-1.0, i - 1.0) / (i * 2.0 - 1.0);
  }
  return n * 4.0;
}

void main() {
    double result;
    long total_time = 0;
    for (int i = 0; i < BENCHMARKS; i++) {
        auto sw = StopWatch(AutoStart.no);
        sw.start();
        result = leibniz(ITERATIONS);
        sw.stop();
        total_time += sw.peek.total!"nsecs";
    }

    writefln("%f\n", result);
    writefln("Avg execution time: %f\n", total_time / BENCHMARKS / 1e9);
}