Question 1

#include <stdio.h>
#include <stdlib.h>

int newsize = 0;                                     //Note: this line for printing the newvec

int* max_seq(int* vec, int size, int divisor)
{
    int* newvec = NULL;
    int index = 0, save[2] = { 0,0 }, compare[2] = { 0,0 };
    for (int i = 0; i < size; i++)
    {
        if (vec[i] % divisor == 0)
        {
            save[1] = i;
        }
        else
        {
            if (save[1] - save[0] > compare[1] - compare[0]) //Check for the max Lengths of sequence
            {
                compare[0] = save[0];                       //Start Index
                compare[1] = save[1];                       //Finish Index
            }

            //Reset
            save[0] = i + 1;
            save[1] = i + 1;
        }
    }
    if (compare[1] != 0)
    {
        newvec = (int*)calloc((compare[1] - compare[0] + 1 + 2), sizeof(int));
        if (newvec == NULL)
            return NULL;
        newvec[0] = compare[0];                          //Start Index
        newvec[1] = compare[1] - compare[0] + 1;         //Length

        newsize = newvec[1] +2;                          //Note: this line for printing the newvec

        int newvecIndex = 2;
        for (int i = compare[0]; i <= compare[1]; i++, newvecIndex++)
        {
            newvec[newvecIndex] = vec[i];
        }
    }
    return newvec;
}

void printArr(int arr[], int size)
{
    for (int i = 0; i < size; i++)
    {
        printf("%d  ", arr[i]);
    }
}

int main()
{
    int vec[] = { 1,2,3,9,5,6,3,-9,7,8,9 };
    int *newvec = max_seq(vec, sizeof(vec) / sizeof(int), 3);
    ///////////////////////////////////////////////////////////////
    printArr(vec, sizeof(vec) / sizeof(int));
    printf("\n");
    printArr(newvec, newsize);
}