redacted.py

def set_value(ary, index: int) -> int:
  if index < len(ary):
    return ary[index]
  else:
    return None

def array_sum(ary) -> int:

  if len(ary) == 0:
    return 0

  curr_index = 0
  current_sum, prev_sum = ary[curr_index], 0
  
  slow_iter = curr_index + 3
  fast_iter = curr_index + 4

  current_val, slow_val, fast_val = 0, 0, 0

  while (curr_index < len(ary)):

    prev_sum = current_sum
    current_val = ary[curr_index]
  
    # look ahead and set our +3 val
    slow_val = set_value(ary=ary, index=(curr_index + 3))
    fast_val = set_value(ary=ary, index=(curr_index + 4))

    # if we are out of bounds on both iters, break out.
    if not slow_val and not fast_val:
      break

    # slow will never be None while fast has a value. So check for the 
    # possibility that fast is None.  Our previous check above
    # will catch the possibility of both being None.
    if not fast_val:
      current_sum += slow_val
      curr_index = curr_index + 3
    elif slow_val >= fast_val:
      current_sum += slow_val
      curr_index = curr_index + 3
    elif fast_val > slow_val:
      current_sum += fast_val
      curr_index = curr_index + 4

    # If we have a value that is best case between slow and fast values
    # is less than our previous.  We can exit as per requirements.
    if prev_sum > current_sum:
      break;
    

  return max(prev_sum, current_sum)
    

test_input_1 = [scrubbed]
print(array_sum(ary=test_input_1))
> 140


test_input_2 = [scrubbed]
print(array_sum(ary=test_input_2))
> 458