1 [54, 26, 93, 17, 77, 31, 44, 55] #升序排序
2 #分解 n//2
3 # [54, 26, 93, 17] [77, 31, 44, 55]
4 #
5 # [54, 26] [93, 17] [77, 31] [44, 55]
6 #
7 # [54] [26] [93] [17] [77] [31] [44] [55]
8
9 #合并
10 # [26,54] [17,93] [31,77] [44,55]
11 #
12 # [17,26,(54,1),93] [31,44,(54,2),55,77]
13 #
14 # [17,26,31,44,54,55,77,93]
15
16 def merg_sort(alist):
17 #分解
18 n=len(alist)
19 #递归的出口 分解到最小
20 if n<=1:
21 return alist
22 mid=n//2
23 left_li=merg_sort(alist[0:mid])
24 right_li=merg_sort(alist[mid:])
25
26 #合并
27 #排序结果列表
28 result=[]
29 left_pointer,right_pointer=0,0
30 while left_pointer<len(left_li) and right_pointer<len(right_li):
31 if left_li[left_pointer] <=right_li[right_pointer]:
32 result.append(left_li[left_pointer])
33 left_pointer += 1
34 else:
35 result.append(right_li[right_pointer])
36 right_pointer += 1
37
38 #退出循环后，将不为空的列表剩余元素添加到result中
39 # result+=left_li[left_pointer:]
40 result.extend(left_li[left_pointer:])
41 result+=right_li[right_pointer:]
42
43 #将最后排序的结果列表返回
44 return result
48 if __name__ =='__main__':
49 alist=[54, 26, 93, 17, 77, 31, 44, 55]
50 print('原来的数组：')
51 print(alist)
52 result=merg_sort(alist)
53 print('排序后：')
54 print(result)
1 原来的数组：
2 [54, 26, 93, 17, 77, 31, 44, 55]
3 排序后：
4 [17, 26, 31, 44, 54, 55, 77, 93]