C++实现并行计算的两种方式

#pragma omp parallel
{
    // 并行计算代码块
}

#include <iostream>
#include <omp.h>

void calculate(int num_threads)
{
    int sum = 0;
#pragma omp parallel for num_threads(num_threads) reduction(+:sum)
    for (int i = 0; i < 10000; i++)
    {
        sum += i;
    }
    std::cout << "Result: " << sum << std::endl;
}

int main()
{
    calculate(2);  // 使用2个线程进行并行计算
    calculate(4);  // 使用4个线程进行并行计算
    return 0;
}

#include <mpi.h>
#include <iostream>

int main(int argc, char** argv)
{
    MPI_Init(&argc, &argv);
    // MPI代码
    MPI_Finalize();
    return 0;
}

// 点对点通信示例
int rank, size;
MPI_Comm_rank(MPI_COMM_WORLD, &rank);  // 获取当前进程的编号
MPI_Comm_size(MPI_COMM_WORLD, &size);  // 获取总进程数

if (rank == 0)
{
    int sendbuf = 100;
    int recvbuf;
    MPI_Send(&sendbuf, 1, MPI_INT, 1, 0, MPI_COMM_WORLD);  // 发送消息
    MPI_Recv(&recvbuf, 1, MPI_INT, 1, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);  // 接收消息
    std::cout << "Process 0 received " << recvbuf << std::endl;   
}
else if (rank == 1)
{
    int sendbuf = 200;
    int recvbuf;
    MPI_Recv(&recvbuf, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);  // 接收消息
    MPI_Send(&sendbuf, 1, MPI_INT, 0, 0, MPI_COMM_WORLD);  // 发送消息
    std::cout << "Process 1 received " << recvbuf << std::endl;   
}

#include <iostream>
#include <mpi.h>

void calculate(int rank)
{
    int sum = 0;
    for (int i = rank; i < 10000; i += 2)
    {
        sum += i;
    }
    int total_sum;
    MPI_Reduce(&sum, &total_sum, 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
    if (rank == 0)
    {
        std::cout << "Result: " << total_sum << std::endl;
    }
}

int main(int argc, char** argv)
{
    int rank, size;
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    calculate(rank);

    MPI_Finalize();
    return 0;
}