#include <stdio.h>  // Standard I/O header file
#include <mpi.h>    // MPI header file
 
#define N 1000  // Size of array
 
int main() {
    int i, rank, size;  // Loop variable, MPI rank, MPI size
    int array[N], local_max, global_max = 0;  // Array, local max, global max
 
    MPI_Init(NULL, NULL);  // Initialize MPI environment
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);  // Get rank of current process
    MPI_Comm_size(MPI_COMM_WORLD, &size);  // Get total number of processes
 
    // Initialize array with rank
    for (i = 0; i < N; i++) {
        array[i] = rank * N + i;  // Each process fills its portion of the array
    }
 
    // Calculate local max
    local_max = array[0];  // Initialize local max with first element
    for (i = 1; i < N; i++) {
        if (array[i] > local_max) {
            local_max = array[i];  // Update local max if current element is greater
        }
    }
 
    // Reduce local max values to find global max
    MPI_Reduce(&local_max, &global_max, 1, MPI_INT, MPI_MAX, 0, MPI_COMM_WORLD);
 
    // Print global max from root process
    if (rank == 0) {
        printf("Global max: %d\n", global_max);
    }
 
    MPI_Finalize();  // Finalize MPI environment
    return 0;
}
 

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