python實現歸併排序

python實現**

建立隨機數組生成程式：random_list.py

#-*- coding:utf-8 -*-

# created date: 2020/03/10
import random
defrandom_list
(n):
"""返回乙個長度為n的隨機數列表，數值為[0,1000)"""
print
("input number is :{}"
.format
(n))
ilist =
for num in
range
(n):
1000))
return ilist
if __name__ ==
"__main__"
:        ilist = random_list(10)
print
(ilist)

#-*- coding:utf-8 -*-

#created date: 2020/03/16
from random_list import random_list
import timeit
import sys
num = sys.ar**[1]
ilist = random_list(
int(num)
)def
merge_sort
(ilist)
:'''建立拆分函式，將乙個數列拆分成兩個數列'''
iflen
(ilist)
<=1:
return ilist
middle =
len(ilist)//2
left, right = ilist[
0:middle]
, ilist[middle:
]"""        通過遞迴的方式，呼叫merge_sort()函式，將拆分後的數列繼續不停的拆分，直到每個數列長度為1
然後呼叫merge_list()函式，將拆分的數列合併排序為1個數列
"""return merge_list(merge_sort(left)
, merge_sort(right)
)def
merge_list
(left, right)
:'''建立合併函式，將兩個數列合併成乙個數列'''
mlist =
while left and right:
if left[0]
>= right[0]
:0))
else:0
))while left:0)
)while right:0)
)return mlist
if __name__ ==
"__main__"
:print
("source list: {}"
.format
(ilist)
)print
("sorted results: {}"
.format
(merge_sort(ilist)))
print
(timeit.timeit(
"merge_sort(ilist)"
,"from __main__ import merge_sort, ilist"
, number =
1000
))

python merge_sort.py 10

input number is :10

source list: [703, 936, 227, 427, 471, 74, 114, 797, 635, 329]
sorted results: [74, 114, 227, 329, 427, 471, 635, 703, 797, 936]
0.0283238

python實現歸併排序

歸併排序，先把陣列按中間分為2個單元，直至每個單元僅包含1個元素，然後依次合併2個單元至一臨時陣列 def merge str,start index,end index,mid,temp j start index k mid 1 i 0while j mid and k end index if...

Python實現歸併排序

def mergesort seq if len seq 1 return seq else mid int len seq 2 lpart mergesort seq mid rpart mergesort seq mid return merge lpart,rpart defmerge lpa...

Python實現歸併排序

歸併排序是典型的分治法的應用 思想 先遞迴分解陣列，再合併陣列 原理 將陣列分解最小之後，然後合併兩個有序陣列，基本思想是比較兩個陣列的最前面的數，誰小就取誰，取完後，將相應的指標後移以為。然後再比較，直到乙個陣列為空，最後把另乙個陣列的剩餘部分複製過來即可。python 實現 歸併排序 def m...