mpi_example.c

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


void print(int vector[], int process, int size){
  // imprime todos os numeros no vetor
  int i;
  printf("processo: %d \n", process);
  for(i = 0; i < size ; i++){
    printf("%d ", vector[i]);
  }
  printf("\n");
}

int sum_largest_vector(int vector[], int vector_size){
  // soma todos os numeros no vetor
  int i, sum = 0;
  for(i = 0; i < vector_size; i++){
    sum += vector[i];
  }
  return sum;
}

int main (int argc, char **argv) { 
  int vetor_size = 10, vector_sum = 0; 
  int num_received = 0, proccess = 1;
  int i, rank, size, type=99; 
  MPI_Status status; 

  // inicializa o mpi
  MPI_Init(&argc, &argv); 
  MPI_Comm_size(MPI_COMM_WORLD, &size); 
  MPI_Comm_rank(MPI_COMM_WORLD, &rank); 
  int *vetor_total = (int*)  calloc (10*size, sizeof(int));
  int *vetor = (int*)  calloc (vetor_size, sizeof(int));
  srand((unsigned)  time(NULL)); 


  if (rank == 0) { 
    // gera numeros aleatorios
      for(i = 0; i < 10* size; i++){ 
      	vetor_total[i] = rand() % 100;
    }
  }

  // divide os dados entre processos
  MPI_Scatter(vetor_total, vetor_size, MPI_INT, vetor, vetor_size, MPI_INT, 0, MPI_COMM_WORLD);

  if (rank != 0){
    // soma os dados no vetor que foi enviado por MPI_Scatter
    vector_sum = sum_largest_vector(vetor, vetor_size);
    // envia a soma para o processo root
    MPI_Send(&vector_sum, 1, MPI_INT, 0, type, MPI_COMM_WORLD); 
  }else{
    for(i = 1; i < size; i++){
      // receve as somas dos processos escravos
      MPI_Recv(&num_received, 1, MPI_INT, i, type, MPI_COMM_WORLD, &status); 
      if (num_received > vector_sum){  
        vector_sum = num_received;
        proccess = i;
      } 
    }
    printf("maior soma: %d do processo %d \n", vector_sum, proccess);
  }

  MPI_Finalize(); 
  return 0; 
}