bad_parallel_prime.c

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

int main(int argc, char *argv[]) {
    MPI_Init(&argc, &argv);
    int rank;
    int size;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    int slice = 45200/32;
    // Let each processor search the space [1412*rank, 1412*(rank+1)]
    int i = 0;
    for (i = slice*rank; i < slice*(rank+1); i++) {
        if (i != 0 && i != 1 && (2000000111 % i) == 0) {
            printf("%d is a factor of 2,000,000,111.\n", i);
            return 1;
        }
    }
    MPI_Finalize();
    printf("Yes, 2,000,000,111 is prime.\n");
    return 0;
}