108 lines
3.3 KiB
Python
108 lines
3.3 KiB
Python
''' mbinary
|
|
#########################################################################
|
|
# File : quickSort.py
|
|
# Author: mbinary
|
|
# Mail: zhuheqin1@gmail.com
|
|
# Blog: https://mbinary.xyz
|
|
# Github: https://github.com/mbinary
|
|
# Created Time: 2018-07-06 10:31
|
|
# Description:
|
|
#########################################################################
|
|
'''
|
|
|
|
def quickSort(lst):
|
|
'''A optimized version of Hoare partition'''
|
|
def partition(a,b):
|
|
pivot = lst[a]
|
|
while a!=b:
|
|
while a<b and lst[b]>pivot: b-=1
|
|
if a<b:
|
|
lst[a] = lst[b]
|
|
a+=1
|
|
while a<b and lst[a]<pivot: a+=1
|
|
if a<b:
|
|
lst[b] = lst[a]
|
|
b-=1
|
|
lst[a] = pivot
|
|
return a
|
|
def _sort(a,b):
|
|
if a>=b:return
|
|
mid = (a+b)//2
|
|
# 三数取中值置于第一个作为 pivot
|
|
if (lst[a]<lst[mid]) ^ (lst[b]<lst[mid]): lst[a],lst[mid] = lst[mid],lst[a] # lst[mid] 为中值
|
|
if (lst[a]<lst[b]) ^ (lst[b]>lst[mid]): lst[a],lst[b] = lst[b],lst[a] # lst[b] 为中值
|
|
i = partition(a,b)
|
|
_sort(a,i-1)
|
|
_sort(i+1,b)
|
|
_sort(0,len(lst)-1)
|
|
return lst
|
|
def quickSort2(lst):
|
|
'''A version of partition from <Introduction of Algorithm>, a little bit slow'''
|
|
def partition(a,b):
|
|
pivot = lst[b]
|
|
j = a-1
|
|
for i in range(a,b):
|
|
if lst[i]<=pivot:
|
|
j+=1
|
|
if i!=j: lst[i], lst[j] = lst[j], lst[i]
|
|
lst[j+1],lst[b] = lst[b],lst[j+1]
|
|
return j+1
|
|
def _sort(a,b):
|
|
if a>=b:return
|
|
mid = (a+b)//2
|
|
# 三数取中值置于第一个作为 pivot
|
|
if (lst[a]<lst[mid]) ^ (lst[b]<lst[mid]): lst[b],lst[mid] = lst[mid],lst[b] # lst[mid] 为中值
|
|
if (lst[a]>lst[b]) ^ (lst[a]>lst[mid]): lst[a],lst[b] = lst[b],lst[a] # lst[b] 为中值
|
|
i = partition(a,b)
|
|
_sort(a,i-1)
|
|
_sort(i+1,b)
|
|
|
|
_sort(0,len(lst)-1)
|
|
return lst
|
|
def quickSort3(lst):
|
|
'''A rear recursive optimization version'''
|
|
def partition(a,b):
|
|
pivot = lst[b]
|
|
j = a-1
|
|
for i in range(a,b):
|
|
if lst[i]<=pivot:
|
|
j+=1
|
|
if i!=j: lst[i], lst[j] = lst[j], lst[i]
|
|
lst[j+1],lst[b] = lst[b],lst[j+1]
|
|
return j+1
|
|
def _sort(a,b):
|
|
while a<b:
|
|
mid = (a+b)//2
|
|
# 三数取中值置于第一个作为 pivot
|
|
if (lst[a]<lst[mid]) ^ (lst[b]<lst[mid]): lst[b],lst[mid] = lst[mid],lst[b] # lst[mid] 为中值
|
|
if (lst[a]>lst[b]) ^ (lst[a]>lst[mid]): lst[a],lst[b] = lst[b],lst[a] # lst[b] 为中值
|
|
i = partition(a,b)
|
|
_sort(a,i-1)
|
|
a = i+1
|
|
_sort(0,len(lst)-1)
|
|
return lst
|
|
|
|
from time import time
|
|
def timer(func,lst,n=100):
|
|
t = time()
|
|
for i in range(n):func(lst)
|
|
t = time()-t
|
|
print('{}: {}s'.format(func.__name__,t))
|
|
return t
|
|
|
|
if __name__ == '__main__':
|
|
from random import randint
|
|
print('5000 items, repeat 100 times for each')
|
|
lst = [randint(0,100) for i in range(5000)]
|
|
timer(quickSort,lst.copy())
|
|
timer(quickSort2,lst.copy())
|
|
timer(quickSort3,lst.copy())
|
|
|
|
lst = [randint(0,100) for i in range(15)]
|
|
print(lst)
|
|
print(quickSort(lst.copy()))
|
|
print(quickSort2(lst.copy()))
|
|
print(quickSort3(lst.copy()))
|
|
|
|
|