#include <iostream>
#include <iomanip>

#include <boost/mpi.hpp>
#include <boost/mpi/environment.hpp>
#include <boost/mpi/communicator.hpp>

namespace mpi = boost::mpi;

using namespace std;

int main([[maybe_unused]] int argc, [[maybe_unused]] char** argv) {

    mpi::environment env{argc, argv};
    mpi::communicator world;

    int limit{100'000'000};

    int world_size;
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);

    int id;
    MPI_Comm_rank(MPI_COMM_WORLD, &id);


    double pi{4};
    double signTerm;
    int skip = 2*(world_size -1);

    if (id > 0) {
       pi = 0;

       int i{id * 2 + 1};
       while (i < limit) {

          if (i%4 == 1) {
              signTerm = 4;
          } else {
              signTerm = -4;
          } 

          pi += signTerm / static_cast<double>(i);

          i += skip;
       }

    }

    double sum{0};

    reduce(world, pi, sum, std::plus<double>(), 0);
    
    if (id == 0) {
       cout << setprecision(10);
       cout << "Pi is about " << sum << endl;
    }


    return 0;
}