rekurzivno_oduzbrajanje - G3 2018/2020 K2

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



#ifndef DEBUG
#define DEBUG(...) printf(__VA_ARGS__)
#endif

#define MAXN 100001

int subsum(int *a, int n) {
    int p = 1;

    if (!n)
    {
        return 0;
    }

    if (n%2==1)
    {
        p = -1;
    }
    return (*a * p) + subsum(a+1, n-1);
}

int main() {
  int n, a[MAXN];
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) {
    scanf("%d", &a[i]);
  }
  printf("%d\n", subsum(a, n));
  return 0;
}