• 求列表全排列

lst = [1,2,3]
l1 = [(x,y,z) for x in lst for y in lst for z in lst if x != y if y != z if x != z]
print(l1)

• 给定一个非负整数num,重复的加每一位,直到最后只剩下一位

例如: num = 38,计算过程如下:

3 + 8 =11

1 + 1 = 2

最后输出结果为2

#递归
def add(num):if len(str(num)) == 1:return numret = 0for i in str(num):ret += int(i)return retreturn(add(ret))
print(add(8))

#累加器
def add(num):ret = 0for i in str(num):ret += int(i)return retdef cacl(num):ret = numwhile ret >= 10:ret = add(ret)return ret
print(cacl(38))#使用列表解析优化版
def add(num):return sum([int(x) for x in str(num)])
def cacl(num):ret = numwhile ret >= 10:ret = add(ret)return ret
print(cacl(38))

• 寻找happy number

happy number值,对一个数字的每一位取平方后相加,对得到的结果反复执行上一步,直到最后只有一位,如果最后结果为1,这个数就为happy number.

例如 19 就是happy number.因为

1^2 + 9^2 = 82

8^2 + 2^2 = 68

6^2 + 8^2 = 100

1^2 + 0^2 + 0^2 = 1

def add(num):ret = 0for i in str(num):ret += (int(i) ** 2)return retdef happy_number(num):results = {num}ret = numwhile ret >= 10:ret = add(ret)if ret in results:return Falseresults.add(ret)return ret == 1for i in range(1,10000):if happy_number(i):print('{0} is happy number'.format(i))
#使用列表解析优化上版
def add(num):return sum([int(x) ** 2 for i in str(num)])def happy_number(num):results = {num}ret = numwhile ret >= 10:ret = add(ret)if ret in results:return Falseresults.add(ret)return ret == 1for i in range(1,10000):if happy_number(i):print('{0} is happy number'.format(i))

• 装饰器

写一个带一个default_user 参数的装饰器,此装饰器检查传入函数的关键字参数,如果没有名为user的参数,使用default_user 作为user 参数传递给函数.

例如:

@inject_user(default_user=comyn)

def do_something(*args,**kwargs):

print(kwargs['user'])

调用do_something() 时能输入comyn

from functools import wraps
def inject_user(default_user):def func(fn):@wraps(fn)def deco(*args, **kwargs):if 'user' not in kwargs.keys():kwargs['user'] = default_userreturn fn(*args, **kwargs)return decoreturn func@inject_user(default_user='comyn')
def do_somethings(*args, **kwargs):print(kwargs['user'])do_somethings()

• 列表匹配

写一个find函数,传入两个列表,其中origin和iterms, items具有默认值[3, 4].查找iterms中每个元素在origin中的所有位置.返回值为字典,key是iterms中的元素,value是位置的元组.

例如:

find([2, 3, 5, 3, 4, 2, 7, 4]) 返回{3:(1, 3), 4:(4, 7)}

def find(origin,items=[3, 4]):fin = dict()for x in iter(items):lst = list()for k, v in enumerate(origin):if x == v:lst.append(k)fin[x] = tuple(lst)return finfind([2, 3, 5, 3, 4, 2, 7, 4])#使用列表解析优化
def find(origin,items=[3, 4]):fin = dict()for x in items:lst = list()[lst.append(k) for k, v in enumerate(origin) if x == v]fin[x] = tuple(lst)return finfind([2, 3, 5, 3, 4, 2, 7, 4])