怎样测试Python程序的时间复杂度

timeit：Python标准库中自带的模块,是一个用来测试代码执行时间的模块。

class timeit.Timer(stmt='pass', setup='pass', timer=<timer function>)
timeit.Timer.timeit(number=1000000)

Timer是测量小段代码执行速度的类，stmt参数是要测试的代码语句（statment)，setup参数是运行代码时需要的设置，timer参数是一个定时器函数，与平台有关。
timeit: Timer类中测试语句执行速度的对象方法。number参数是测试代码时的测试次数，默认为1000000次。

下面是timeit的示例

from timeit import Timer 
def solution1():
    A= [4,3,4,4,4,2]
    # write your code in Python 3.6

    len_A = len(A)
    size = 0
    leader = -1
    index = -2
    result = 0
    count_left = 0
    
    for i in A:
        if size ==0:
            leader = i
            size +=1
            index +=1
        else:
            if leader ==i:
                size +=1
            else:
                size-=1
    leader_count = len([i for i in A if i == leader]) # count
    if leader_count <= len_A//2:
        return 0
        
    for i in range(len_A):
        if A[i] == leader:
            count_left +=1
        if count_left>(i+1)//2 and leader_count-count_left>(len_A-i-1)//2:
            result +=1   
    return result


t1 = Timer("solution1()","from __main__ import solution1")
print("my solution",t1.timeit(number=1000), "seconds")

结果

my solution 0.004183967000244593 seconds