#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>

#define MASTER 0             /*Procesul master */
#define TRIES 50000          /*Numarul de incercari-generari de numere aleatoare*/
#define ITER 100             /*Numaarul de iteratii pt cele TRIES incercari*/

#define SQR(x) ((x)*(x))

double hit (int tries);

int main (int argc, char ** argv)
{
    double local_pi,  /*valoarea pi locala*/
           sum_pi,    /*buffer pentru suma valorile locale*/
	   aver_pi,   /*valoarea medie a tuturor iteratiilor*/
	   pi;        /*valoarea pi generata de procesul master*/

    int my_rank, nproc, rc, i;
    MPI_Status status;

    MPI_Init(&argc,&argv);
    MPI_Comm_size(MPI_COMM_WORLD, &nproc);
    MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
    printf("Procesul MPI %d a pornit...\n", my_rank);

    srandom(my_rank); //initializez generatorul de numere aleatoare cu rangul procesului.

    aver_pi=0.;
    for(i = 0;i < ITER; i++)
    {
    local_pi=hit(TRIES);
    rc=MPI_Reduce(&local_pi, &sum_pi, 1, MPI_DOUBLE, MPI_SUM, MASTER, MPI_COMM_WORLD);
    if(rc != MPI_SUCCESS)
        printf("Procesul %d: eroare la operatia MPI_Reduce\n", my_rank);

    /*Master computes average for this iteration and all iterations*/
    if(my_rank == MASTER)
    {
        pi=sum_pi/nproc;
        aver_pi=((aver_pi * i) + pi)/(i + 1);
        printf("\t Dupa %d incercari, valoarea medie a lui pi = %10.8f\n", (TRIES * (i+1)),aver_pi);
    }
    }
    if (my_rank == MASTER)
    printf("\nValoarea aproximativa a lui Pi: 3.1415926535897 \n");
    MPI_Finalize();
    return 0;
}

double hit (int tries)
{
    double x_coord, y_coord, pi, r;
    int score = 0, n;
    unsigned int nrconst = 2 << (31-1);
    for (n=1; n<=tries; n++)
    {
      r = (double) random()/nrconst;
      x_coord = 2.*r -1.;
      r = (double) random()/nrconst;
      y_coord = 2.*r -1.;
      if((SQR(x_coord) + SQR(y_coord)) <= 1.0)
	  score++;
    }
    pi = 4.0 * (double)score/(double)tries;
    return pi;
}