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

const long A = 1000000000;

int main(int argc, char *argv[])
{
	int i, j;
	int id; //Process rank
	int np; //Num of processes
	double x, y, PI; //coordinates
	long in, globalIn; // number of points inside the circle
	double elapsed_time;
	double PI25DT = 3.141592653589793238462643;

	MPI_Init(&argc, &argv);
	MPI_Comm_rank(MPI_COMM_WORLD, &id);
	MPI_Comm_size(MPI_COMM_WORLD, &np);
	
	MPI_Barrier(MPI_COMM_WORLD);
        elapsed_time = - MPI_Wtime();
	
	srand ( time(NULL)*id );
	in = 0;
	
	for(i = 0; i < A/np; i++)
	{
		x = ((double)rand() / RAND_MAX);
		y = ((double)rand() / RAND_MAX);
		
		if (x*x + y*y <= 1) in++; 		
	}
	
	MPI_Reduce(&in, &globalIn, 1, MPI_LONG, MPI_SUM, 0,  MPI_COMM_WORLD);
	
	elapsed_time += MPI_Wtime();
	
	if(id == 0)
	{
		PI = (double)4*globalIn/A;
		printf("PI = %26.25f,  and elapsed time is %f\n",PI, elapsed_time);
		printf("PI25 - PIour = %26.25f\n",PI25DT - PI);
	}

	MPI_Finalize();
	
	return 0;
}