How to evenly distribute an array with Scatterv - c++

Question

My program is meant to take an array size and the elements of that particular array from the user.
However, I want the program to be able to distribute the array elements evenly for any number of processors used.
I think the problem is on the displs array, but even after countless try-outs, I don't seem to be reaching any logical conclusion.
Let's say I enter a sequence of 7 numbers -> 1,2,3,4,5,6,7
I will have an output as such:
processor 0
arr[0] = 1
arr[1] = 2
arr[2] = 3
processor 1
arr[0] = 4
arr[1] = 5
processor 2
arr[0] = 7
arr[1] = 32767
The code is the following:
#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#define ARRAY_SIZE 100
int main(int argc, char **argv)
{
int myrank, wsize;
int i,N;
int *arr,*displs, *arr_r, *sendcount;
int sum1=0;
int portion,remainder,x,y;
int root;
MPI_Status status;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
MPI_Comm_size(MPI_COMM_WORLD, &wsize);
if(myrank == 0)
{
printf("Enter number N of integers\n");
scanf("%d", &N);
arr = (int*)malloc(N*sizeof(int));
for(i = 0; i < N; i++)
{
printf("Enter number %d\n", i+1);
scanf("%d",&arr[i]);
}
}
MPI_Bcast(&N, 1, MPI_INT, 0, MPI_COMM_WORLD);
portion = N / wsize;
remainder = N % wsize;
x = portion;
y = portion +1;
displs = (int*)malloc(N*sizeof(int));
sendcount = (int*)malloc(N*sizeof(int));
for(i=0; i < N; i++)
{
if(myrank < remainder)
{
sendcount[i] = portion + (remainder);
displs[i] = (portion + (remainder)) * i;
}
else if(remainder == 0)
{
sendcount[i] = portion;
displs[i] = portion *i;
}
else
{
sendcount[i] = portion;
displs[i] = portion * i;
}
}
arr_r = (int*)malloc(N *sizeof(int));
MPI_Scatterv(arr, sendcount, displs, MPI_INT, arr_r, N, MPI_INT, 0, MPI_COMM_WORLD);
if(myrank < remainder)
{
printf("process %d \n",myrank);
for(i = 0; i < portion + 1; i++)
{
printf("Arr[%d] = %d\n",i,arr_r[i]);
}
}
else if(remainder == 0)
{
printf("process %d \n",myrank);
for(i = 0; i < portion; i++)
{
printf("Arr[%d] = %d\n",i,arr_r[i]);
}
}
else
{
printf("process %d \n",myrank);
for(i = 0; i < portion; i++)
{
printf("Arr[%d] = %d\n",i,arr_r[i]);
}
}
MPI_Finalize();
return 0;
}