冒泡算法

先理解a=123,b=321,两个互换的方法和思路，其实就是找个中间变量存放其值

>>> a=123

>>> b=321

>>> tmp=a

>>> a=b

>>> b=tmp

>>> a,b

(321, 123)

 

 

 

li = [13,22,6,99,11]

 

请按照一下规则计算：

13 和 22 比较，将大的值放在右侧，即：[13, 22, 6, 99, 11]

22 和 6 比较，将大的值放在右侧，即：[13, 6, 22, 99, 11]

22 和 99 比较，将大的值放在右侧，即：[13, 6, 22, 99, 11]

99 和 11 比较，将大的值放在右侧，即：[13, 6, 22, 11, 99]

......

13 和 6 比较，将大的值放在右侧，即：[6, 13, 22, 11, 99,]

 

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第一步：

li = [13, 22, 6, 99, 11]

for m in range(4): # 等价于 #for m in range(len(li)-1):

if li[m]> li[m+1]:

temp = li[m+1]

li[m+1] = li[m]

li[m] = temp

 

第二步：

li = [13, 22, 6, 99, 11]

for m in range(4): # 等价于 #for m in range(len(li)-1):

if li[m]> li[m+1]:

temp = li[m+1]

li[m+1] = li[m]

li[m] = temp

 

for m in range(3): # 等价于 #for m in range(len(li)-2):

if li[m]> li[m+1]:

temp = li[m+1]

li[m+1] = li[m]

li[m] = temp

 

for m in range(2): # 等价于 #for m in range(len(li)-3):

if li[m]> li[m+1]:

temp = li[m+1]

li[m+1] = li[m]

li[m] = temp

 

for m in range(1): # 等价于 #for m in range(len(li)-4):

if li[m]> li[m+1]:

temp = li[m+1]

li[m+1] = li[m]

li[m] = temp

print li

 

第三步：

li = [13, 22, 6, 99, 11]

for i in range(1,5):

for m in range(len(li)-i):

if li[m] > li[m+1]:

temp = li[m+1]

li[m+1] = li[m]

li[m] = temp

实际代码：

import random
import time

def bubble_sort(array):
    for i in range(len(array)):
        for j in range(len(array)-1-i,):
            if array[j] > array[j+1]:
                tmp = array[j]
                array[j] = array[j+1]
                array[j+1] = tmp


if __name__ == '__main__':
    array = []
    for i in range(20000):
        array.append(random.randrange(100000))
        
    time_start = time.time()
    bubble_sort(array)
    time_end = time.time()



print (array)
print ("cost:",time_end-time_start)

#冒泡算法：4.35s(5000个数字),17.60（10000个数字），70（20000个数字）