2019.9.24-归并排序（代码）

# coding:utf-8

def merge_sort(alist):
"""歸幷排序"""
n = len(alist)
if n <= 1:
return alist
mid = n//2

# left 採用歸幷排序後形成的有序的新的列表
left_li = merge_sort(alist[:mid])

# right 採用歸幷排序後形成的有序的新的列表
right_li = merge_sort(alist[mid:])

# 將兩個有序的子序列合並爲一個新的整體
# merge(left, right)
left_pointer, right_pointer = 0, 0
result = []

while left_pointer < len(left_li) and right_pointer < len(right_li):
if left_li[left_pointer] <= right_li[right_pointer]:
result.append(left_li[left_pointer])
left_pointer += 1
else:
result.append(right_li[right_pointer])
right_pointer += 1

result += left_li[left_pointer:]
result += right_li[right_pointer:]
return result

if __name__ == "__main__":
li = [54, 26, 93, 17, 77, 31, 44, 55, 20]
print(li)
sorted_li = merge_sort(li)
print(li)
print(sorted_li)

 

执行结果