python3中的希尔排序

def shell_sort(alist):
    n = len(alist)
    # 初始步长
    gap = round(n / 2)
   
    while gap > 0:
        # 按步长进行插入排序
        for i in range(gap, n):
            j = i
            # 插入排序
            while j>=gap and alist[j-gap] > alist[j]:
                alist[j-gap], alist[j] = alist[j], alist[j-gap]
                j -= gap
        # 得到新的步长
        gap = round(gap / 2)

alist = [54,26,93,17,77,31,44,55,20,99,64]
shell_sort(alist)
print(alist)