besempre_zjl：第一题就是每次算以下更新的差值，不要去每次都k个求和，代码量也不大 def f(arr, n, k): ret_idx = 0 delta, min_delta = 0, 0 for i in range(k, n): new_delta = delta + arr[i] - arr[i - k] if new_delta < min_delta: min_delta = new_delta ret_idx = i - k + 1 delta = new_delta return ret_idx + 1 哈哈关键是第二题，搞了半天，那个测试用例2为啥是“No”，搞不懂