fib4

int Fib::find_fib(int n)
{
  int v[3];
  int i;

  if (n == 0 || n == 1) return 1;

  v[0] = 1;
  v[1] = 1;
  for (i = 2; i <= n; i++) {
    v[2] = v[0] + v[1];
    v[0] = v[1];
    v[1] = v[2];
  }

  return v[2];
}

//instead of using a cache that is n items in size, let's just use three. This saves hella memory with large inputs