The max heap solution gives 23 for following inputs:

input = [3, 5, 8, 7], k1=2, k2=7

when the answer should be 15 because it's popping off all elements from max_heap in the last for loop.

I needed to change it to as follows to get the correct answer:

upper_bound = min (k2 - k1 - 1, input_size - k1)

for i in range (upper_bound): if max_heap: sum += -heapq.heappop(max_heap) else: break

If i use k2=9 instead, I get index out of range error from official max heap solution because it tries to pop too many times