Python数据结构———合并排序

合并排序：通过将数据分为n个组，通过n步分别排序并合并；是一个稳定的排序算法；通过比较 log2^n 次处理；时间复杂度：O(n*log2^n)；额外空间：O(n)；

list1 = [20, 45, 51, 88, 99999]
list2 = [98, 10, 23, 15, 99999]
list3 = []


def merge_sort():
    global list1
    global list2
    global list3

    select_sort(list1, len(list1) - 1)
    select_sort(list2, len(list2) - 2)

    My_Merge(len(list1) - 1, len(list2) - 1)


def select_sort(data, size):
    for base in range(size - 1):
        small = base
        for j in range(base + 1, size):
            if data[j] < data[small]:
                small = j
        data[small], data[base] = data[base], data[small]


def My_Merge(size1, size2):
    global list1
    global list2
    global list3

    index1 = 0
    index2 = 0
    for index3 in range(len(list1) + len(list2) - 2):
        if list1[index1] < list2[index2]:
            list3.append(list1[index1])
            index1 += 1
        else:
            list3.append(list2[index2])
            index2 += 1


if __name__ == '__main__':
    merge_sort()
    print(list1)
    print(list2)
    print(list3)