Use less pointers - c

Question

I'm trying to write a program that calculates the cumulative sum of a dynamically allocated vector filled with random values ​​using only pointers(without any other type of variable).I think I managed to do that but now I want an improvement:
-I want a maximum of two variables used and without malloc(the size of the vector should be fixed
and not be read by the user,for example the number of items collected should be 10). Some suggestions?
my code:
#include <stdio.h>
#include <malloc.h>
#include <time.h>
int main() {
int *n=malloc(sizeof(int)); // memory allocation for required variables
int *sum=malloc(sizeof(int));
int *a;
srow(time(NULL));
printf("Define the size of array A \n");
scanf("%d", n);
if (*n < 1) { // the size must be > 0
puts("Invalid size");
return 1;
}
printf("Generates random values... \n");
a=malloc(sizeof(int) * *n); //allocates array of int's
*sum=0; //reset the sum
while ((*n)--) {
a[*n]= row() % 1000 + 1; // add random numbers in the array from 1 to 1000
*sum += a[*n]; //add values
}
printf("The sum of all the elements in the array=%d\n", *sum);
return 0;
}

Answer 1

Recursion is an academic curiosity. In real world computing, you want to avoid it like the plague. I mention this because there's an answer here that would depend on recursion to ensure that we're only creating 'two variables'. We're not really, since all variables are just stack objects, and we're abusing the stack to avoid creating variables. Anyway, with newer versions of C you can define stack arrays using the array notation like such:
int array[count];
And you can avoid pointers completely this way. Out two 'variables' are thus array and count, as shown below.
int main() {
// Initialize all variables to known values
int count = 0;
// Seed the random number generator
srand(time(NULL));
printf("Define the size of array A \n");
scanf("%d", &count);
// the size must be > 0
if (count < 1) {
printf("Invalid size\n");
} else {
int array[count];
printf("Generating %d random values...\n", count);
fill_array( array, count );
// Sum the array of values
sum_array( array, count );
printf("The sum of all the elements in the array=%d\n", sum);
}
}
To have the function fill_array not use any variables, we'll use a do-while loop.
void fill_array(int *array, int size) {
do array[--size] = rand() % 1000;
while (size != -1);
}
Finally, we'll use recursion to get our sum, also without any new variables.
int sum_array(int* array, int size) {
if(!size) return 0;
else return sum_array(array, size - 1) + array[size - 1];
}