python（三）6种排序算法性能比较（冒泡、选择、插入、希尔、快速、归并）

# coding:utf-8

import random
import time

def bubble_sort(alist):
"""冒泡"""
n = len(alist)
for j in range(n-1):
count = 0
for i in range(0, n-1-j):
if alist[i] > alist[i+1]:
alist[i],alist[i+1] = alist[i+1], alist[i]
count += 1
if 0 == count:
return

def select_sort(alist):
"""选择"""
n = len(alist)
for j in range(n-1):
min_index = j
for i in range(j+1, n):
if alist[min_index] > alist[i]:
min_index = i
alist[j], alist[min_index] = alist[min_index], alist[j]

def insert_sort(alist):
"""插入"""
n = len(alist)
for j in range(1, n):
i = j
while i > 0:
if alist[i] < alist[i-1]:
alist[i], alist[i-1] = alist[i-1], alist[i]
i -= 1
else:
break

def shell_sort(alist):
"""希尔"""
n = len(alist)
gap = n // 2
while gap > 0:
for j in range(gap, n):
i = j
while i > 0:
if alist[i] < alist[i-gap]:
alist[i], alist[i-gap] = alist[i-gap], alist[i]
i -= gap
else:
break
gap //= 2

def quick_sort(alist, first, last):
"""快速"""
if first >= last:
return
mid_value = alist[first]
low = first
high = last
while low < high:
while low < high and alist[high] >= mid_value:
high -= 1
alist[low] = alist[high]
while low <high and alist[low] < mid_value:
low += 1
alist[high] = alist[low]
alist[low] = mid_value
quick_sort(alist, first, low-1)
quick_sort(alist, low+1, last)

def merge_sort(alist):
"""归并"""
n = len(alist)
if n <= 1:
return alist
mid = n//2
left_li = merge_sort(alist[:mid])
right_li = merge_sort(alist[mid:])
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__":
seq = list(range(1, 10000))
li = random.sample(seq, 1000)
print(li)
start = time.clock()
# bubble_sort(li)# 0.118379
# select_sort(li)# 0.049213
# insert_sort(li)# 0.097392
# shell_sort(li)# 0.011831
quick_sort(li, 0, len(li) - 1)# 0.003824
# li = merge_sort(li)# 0.005906
end = time.clock()
print("time: %f " % (end - start))
print(li)