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  1. #include <stdio.h>
  2. #include <mpi.h>
  3.  
  4. int main(int argc, char *argv[]) {
  5.     int pid, nprocs;
  6.     int N;  // Size of the array
  7.     int *tableau = NULL;  // Pointer to hold the user-entered array
  8.     int taille_par_process, somme_locale = 0, somme_totale = 0;
  9.  
  10.     MPI_Init(&argc, &argv);
  11.     MPI_Comm_rank(MPI_COMM_WORLD, &pid);
  12.     MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
  13.  
  14.     if (pid == 0) {
  15.         // Process 0 asks the user for the size of the array
  16.         printf("Enter the size of the array (divisible by %d): ", nprocs);
  17.         scanf("%d", &N);
  18.  
  19.         // Allocate memory for the array
  20.         tableau = (int *)malloc(N * sizeof(int));
  21.  
  22.         // Get the elements from the user
  23.         printf("Enter %d integers:\n", N);
  24.         for (int i = 0; i < N; i++) {
  25.             scanf("%d", &tableau[i]);
  26.         }
  27.     }
  28.  
  29.     // Broadcast the size of the array to all processes
  30.     MPI_Bcast(&N, 1, MPI_INT, 0, MPI_COMM_WORLD);
  31.  
  32.     // Check if the size is divisible by the number of processes
  33.     if (N % nprocs != 0) {
  34.         if (pid == 0) {
  35.             printf("Error: Array size must be divisible by the number of processes.\n");
  36.         }
  37.         MPI_Finalize();
  38.         return -1;
  39.     }
  40.  
  41.     // Calculate the size of each process's portion
  42.     taille_par_process = N / nprocs;
  43.     int sous_tableau[taille_par_process];  // Local array for each process
  44.  
  45.     // Scatter the array to all processes
  46.     MPI_Scatter(tableau, taille_par_process, MPI_INT,
  47.                 sous_tableau, taille_par_process, MPI_INT,
  48.                 0, MPI_COMM_WORLD);
  49.  
  50.     // Each process calculates the sum of its portion
  51.     for (int i = 0; i < taille_par_process; i++) {
  52.         somme_locale += sous_tableau[i];
  53.     }
  54.     printf("Process %d: Local sum = %d\n", pid, somme_locale);
  55.  
  56.     // Reduce the local sums into the total sum at process 0
  57.     MPI_Reduce(&somme_locale, &somme_totale, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
  58.  
  59.     // Process 0 prints the total sum
  60.     if (pid == 0) {
  61.         printf("Total sum of the array elements = %d\n", somme_totale);
  62.         free(tableau);  // Free the allocated memory
  63.     }
  64.  
  65.     MPI_Finalize();
  66.     return 0;
  67. }
  68.  
Success #stdin #stdout #stderr 0.33s 40548KB
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stdin
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Standard input is empty
stdout
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Standard output is empty
stderr
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Error: unexpected symbol in "int main"
Execution halted
https://ideone.com/U0dVfG
language:
R (R 3.5.2)
created:
2 days ago
visibility:
public

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