#include <iostream>
#include <iomanip>
#include <omp.h>
#include <vector>

using namespace std;

void Greeting();

int main() {

     int numberOfThreads = 8;

     vector<long > hitArray(numberOfThreads,0);
     int size{200'000'000};

     #pragma omp parallel num_threads(numberOfThreads) 
     {
         int id{omp_get_thread_num()};

         long int hits = 0;
         double x, y;
         unsigned int seed = time(nullptr) * id;

         #pragma omp for 
         for(int i = 0; i < size; ++i) {
             x = rand_r(&seed) / static_cast<double>( RAND_MAX);
             y = rand_r(&seed) / static_cast<double>( RAND_MAX);

             if ((x*x +y*y ) <= 1 ) {
                 ++hits;
             }
         }
         hitArray[id] = hits; 
     }

     cout << fixed << setprecision(10);
     long double pi = 0;
     for (int i = 0; i < numberOfThreads; ++i)  {
        pi += hitArray[i];
     }

     cout << 4.0 * pi / static_cast<double>(size) << endl;

     return 0;
}