#include "mpi.h"
#include <math.h>
#include <stdio.h>

#define SIZE1 4
#define SIZE2 4

int main( int argc, char *argv[] )
{
    int n, myid, numprocs, i;
    long sum, localsum;
    double time;
    int matr[SIZE1][SIZE2];
    int vect[SIZE2];
    int locans[SIZE1];
    int ans[SIZE1];
    int j=0;
    int k=0;

    while(j<SIZE1){
        while(k<SIZE2){
            matr[j][k]=rand();
        while(k<SIZE2){
            matr[j][k]=rand();
        //    printf("%i ",matr[j][k]);
            vect[k++]=rand();
        }
//      printf("\n");
        locans[j++]=0;
        k=0;
    }


   // PART 1: Initialization
    MPI_Datatype size1type, size2type;

    MPI_Init(&argc,&argv);
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
    MPI_Comm_rank(MPI_COMM_WORLD,&myid);

    // PART 2: broad-cast the number of intervals
    if (myid == 0) {
            n = numprocs;
    }
            n = numprocs;
    }
    //MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
    //create a new broadcast type for the arrays
    MPI_Type_contiguous(SIZE2,MPI_INT,&size2type);
    MPI_Type_commit(&size2type);
    MPI_Type_contiguous(SIZE1,MPI_INT,&size1type);
    MPI_Type_commit(&size1type);
    int sendcount=0;
    while(sendcount<SIZE1){
        MPI_Bcast(&matr[sendcount++][0],1,size2type,0,MPI_COMM_WORLD);
    }
    MPI_Bcast(&vect[0],1,size2type,0,MPI_COMM_WORLD);


    // PART 3: record the clock time
    time = MPI_Wtime();

    // PART 4: compute
    j=myid;
    k=0;
    while(j<SIZE1){
        while(k<SIZE2){
//            printf("%i ", matr[j][k]);
            locans[j]+=matr[j][k]*vect[k++];
        }
        j+=numprocs;
        k=0;
//      printf("\n");
    }

    // PART 5: reduce
//    MPI_Reduce(&locans, &ans, 1, size1type, MPI_SUM, 0, MPI_COMM_WORLD);
//    MPI_Gather(&locans,SIZE1,MPI_INT,&ans,SIZE1,MPI_INT,0,MPI_COMM_WORLD);

    j=0;
    while(j<SIZE1){
//        MPI_Gather(&locans[j],1,MPI_INT,&ans[j++],1,MPI_INT,0,MPI_COMM_WORLD);
        MPI_Reduce(&locans[j], &ans[j], 1, MPI_INT, MPI_SUM, 0, MPI_COMM_WORLD);
    }

    if (myid == 0) {
        printf("The value is:\n[ ");
        int l=0;
        while(l<SIZE1){
            printf("%i\n  ",ans[l++]);
        }
        printf(" ]\n");
        printf("Time cost = %g\n", MPI_Wtime()-time);
    }

    MPI_Finalize();
    return 0;
}