def merge(row_data, result_data, start, center, end):
    i = start
    j = center + 1
    k = start

    while i <= center and j <= end:
        if result_data[i] <= result_data[j]:
            row_data[k] = result_data[i]
            k = k + 1
            i = i + 1
        else:
            row_data[k] = result_data[j]
            k = k + 1
            j = j + 1
    if i <= center:
        while i <= center:
            row_data[k] = result_data[i]
            k = k + 1
            i = i + 1

    if j <= end:
        while j <= end:
            row_data[k] = result_data[j]
            k = k + 1
            j = j + 1
    print("合并结果")
    print(row_data)
    # result 的 值 也要改变； 如果不改变，下次 比较时，会出错；
    for x in range(start, end + 1):
        result_data[x] = row_data[x]   # row_data 是排序号的数据； 将排好序的数据 赋值给 result_data；


# row_data: 原始数据， result_data： 结果数据
def merge_sort(row_data, result_data, start, end):
    if start == end:
        result_data[start] = row_data[start]
    else:
        center = (start + end) // 2
        merge_sort(row_data, result_data, start, center)
        merge_sort(row_data, result_data, center+1, end)
        merge(row_data, result_data, start, center, end)


def test_data():
    data = [23, 13, 49, 6, 31, 19, 28]  # 数组是 引用；
    result = list(range(len(data)))
    print(result)
    merge_sort(data, result, 0, len(data)-1)
    print("运行结果")
    print("排序结果：")
    print(result)


test_data()