常用算法及效率分析

#_*_coding:utf-8_*_

'''
冒泡排序
'''

import random,time

l=range(1000)
print(l)

random.shuffle(l)
print(l)

def timer(func):
def _wrapper(*args,**kwargs):
start_time=time.time()
res=func(*args,**kwargs)
stop_time=time.time()
print('the func %s run time is %s' %(func,stop_time-start_time))
return _wrapper

@timer
def bubble_sort(l):
for j in reversed(range(len(l))):
for i in range(len(l)-1):
if l[i] > l[i+1]:
tmp=l[i]
l[i]=l[i+1]
l[i+1]=tmp
#l[i],l[i+1]=l[i+1],l[i]
print(l)

bubble_sort(l)

运行：

the func bubble_sort run time is 0.110095024109

#_*_coding:utf-8_*_

'''
冒泡排序
'''

import random,time

l=range(1000)
print(l)

random.shuffle(l)
print(l)

def timer(func):
def _wrapper(*args,**kwargs):
start_time=time.time()
res=func(*args,**kwargs)
stop_time=time.time()
print('the func %s run time is %s' %(func.__name__,stop_time-start_time))
return _wrapper

@timer
def bubble_sort(l):
for j in reversed(range(len(l))):
for i in range(len(l)-1):
if l[i] > l[i+1]:
l[i],l[i+1]=l[i+1],l[i]
print(l)

bubble_sort(l)

运行：
the func bubble_sort run time is 0.105001926422

#_*_coding:utf-8_*_

'''
冒泡排序
'''

import random,time

l=range(1000)

print(l)
random.shuffle(l)
print(l)

def timer(func):
def _wrapper(*args,**kwargs):
start_time=time.time()
res=func(*args,**kwargs)
stop_time=time.time()
print('the func %s run time is %s' %(func.__name__,stop_time-start_time))
return res
return _wrapper

@timer
def bubble_sort(l):
l1 = reversed(range(len(l)))
l2 = range(len(l) - 1)
for j in l1:
for i in l2:
if l[i] > l[i+1]:
l[i],l[i+1]=l[i+1],l[i]

print(l)

bubble_sort(l)

运行：
the func bubble_sort run time is 0.0980820655823

#_*_coding:utf-8_*_

'''
选择排序：
1.核心原理：每次比较的成果是取出最小值的索引，然后和未排序的第一个值交换顺序（第一次比较，未排序的第一个值的索引就是0）
2.实现：两个for循环，外层循环控制未排序值的比较次数，内层循环控制每次取一个最小的值放左边
'''

import random,time

l=range(1000)

print(l)
random.shuffle(l)
print(l)

def timer(func):
def _wrapper(*args,**kwargs):
start_time=time.time()
res=func(*args,**kwargs)
stop_time=time.time()
print('the func %s run time is %s' %(func,stop_time-start_time))
return res
return _wrapper

@timer
def choice_sort(l):

for j in range(len(l)):
smallest_index=j
for i in range(j,len(l)):
if l[i] < l[smallest_index]:
smallest_index = i

l[j],l[smallest_index]=l[smallest_index],l[j]

print(l)

choice_sort(l)

运行：

the func choice_sort run time is 0.0295298099518

#_*_coding:utf-8_*_

'''
插入排序：
1.核心原理：
2.实现：
'''

import random,time

l=range(1000)

print(l)
random.shuffle(l)
print(l)

def timer(func):
def _wrapper(*args,**kwargs):
start_time=time.time()
res=func(*args,**kwargs)
stop_time=time.time()
print('the func %s run time is %s' %(func,stop_time-start_time))
return res
return _wrapper

@timer
def insert_sort(l):
for j in range(len(l)):
position=j
while position > 0 and l[position] < l[position-1]:
l[position],l[position-1]=l[position-1],l[position]
position-=1

insert_sort(l)

运行：
the func insert_sort run time is 0.0595319271088