ผลรวมช่วงต่อเนื่องสูงสุด

def maximum_subarray(values):
    if type(values) not in (list, tuple) or len(values) > 1000 or any(type(v) is not int or abs(v) > 10**9 for v in values):
        raise ValueError("subarray.input")
    if not values:
        return None
    best = None
    total, start = 0, 0
    for end, value in enumerate(values, 1):
        if total < 0:
            total, start = 0, end - 1
        total += value
        candidate = (total, start, end)
        if best is None or (-total, start, end) < (-best[0], best[1], best[2]):
            best = candidate
    return best