新建一个时间计算程序，cal_time.py 

    1. #用于计算时间复杂度的程序
    2. import time
    4. def cal_time(func):
    5.     def wrapper(*args,**kwargs):
    6.         t1 = time.time()
    7.         result = func(*args, **kwargs)
    8.         t2 = time.time()
    9.         print("%s running time: %s secs." % (func.__name__,t2 - t1))
    10.         return result
    12.     return wrapper

    新建一个 查找比较的程序
    这里采用了装饰器；

    from  cal_time import *

@cal_time
def linear_search(li,val):
    for ind,v in enumerate(li):
        if v == val:
            return ind
        else:
            return None

@cal_time
def binary_search(li,val):
    left=0
    right=len(li)-1
    while left<=right:    #说明候选区有值；
        mid = (left+right) // 2
        if li[mid] == val:
            return mid
        elif li[mid] > val:
            right = mid -1
        else: #mid<val 说明待查找的值在右侧；
            left = mid +1
    else:
        return None


li=list(range(1000000))
linear_search(li,543)
binary_search(li,543)