我需要使用MPI_Scatter将数组片段发送到所有进程，然后获取所有元素的总和。我应该在哪里初始化数组然后分散它？在根目录上？

如果我在根级别上初始化数组，则其他级别不会获取其数据。否则，我可以为每个人初始化数组（在if(rank == root)...else中），但这意味着我多次创建了数组。

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

using namespace std;

int main(int argc,char* argv[])
{
    int size;
    int rank;

    srand(time(NULL));

    MPI_Init(&argc,&argv);

    MPI_Comm_size(MPI_COMM_WORLD,&size);
    MPI_Comm_rank(MPI_COMM_WORLD,&rank);

    int arr_size = size * 2;
    int block = arr_size / (size);

    int* B = new int[block];

    if (rank == 0)
    {
        int* A = new int[arr_size];

        cout << "generated array: " << endl;
        for (int i = 0; i < arr_size; i++)
        {
            A[i] = rand() % 100;
            cout << A[i] << " ";
        }
        cout << endl;

        MPI_Scatter(A,block,MPI_INT,B,MPI_COMM_WORLD);       
    }

    cout << "process " << rank << " received: " << endl;
    for (int i = 0; i < block; i++)
    {
        cout << B[i] << " ";
    }
    cout << endl;

    int local_sum = 0;
    for (int i = 0; i < block; i++)
    {
        local_sum += B[i];
    }
    cout << "sum in process " << rank << " = " << local_sum << endl;
    cout << endl;

    int global_sum;
    MPI_Reduce(&local_sum,&global_sum,1,MPI_SUM,MPI_COMM_WORLD);

    if (rank == 0)
    {
        cout << "sum = " << global_sum << endl;
    }

    MPI_Finalize();
    return 0;
}

我得到了这样的信息（只有根排名获得了它的数据）：

process 1 received:
process 3 received:
-842150451 -842150451
-842150451 -842150451
sum in process 1 = -1684300902
sum in process 3 = -1684300902


process 2 received:
-842150451 -842150451
sum in process 2 = -1684300902

process 0 received:
4 9
sum in process 0 = 13

sum = -757935397