day10练习

一、递归
          1.1 使用递归实现：计算某个数的阶乘

import  math

def re_mul(n):
    if n <= 0:
        return 1
    return n*re_mul(n-1)


while True:
    num = input("请输入数字:\n")
    if(num == "退出"):
        break
    try:
        num_int = math.floor(eval(num))
        print(re_mul(num_int))
    except:
        print("输入错误")

          1.2 用递归函数来实现获取斐波拉契数列中第n个数字的值
ps（斐波那契数列：从3三个数开始,后一个数等于前面两个数的和：
0，1，1，2，3，5，8，13，21，34，55，89，144……

）

import  math

def func(num0,num1,num_index):
#斐波那契数列
    if num_index == 1:
        return num0
    if num_index == 2:
        return num1

    return func(num0,num1,num_index-1)+func(num0,num1,num_index-2)

while True:
    num0 = input("请输入第一个数字:\n")
    num1 = input("请输入第二个数字:\n")
    if(num0 == "退出" or num1 == "退出" ):
        break
    try:
        num0_int = eval(num0)
        num1_int = eval(num1)
        while True:
            num_index = input("请输入第几项:\n")
            if num_index == "exit":
                break
            num_index_int = eval(num_index)
            print("第一项为{}，第二项为{}".format(num0,num1))
            print("斐波那契数列第{}为{}".format(num_index,func(num0_int,num1_int,num_index_int)))
    except:
        print("输入错误")

二、函数封装
   2.1 封装函数实现如下要求
           例如：输入2，5
               则求：2 + 22＋222 + 2222＋22222的和

import  math

def re_func(num,n):
#数字重复
    if n <= 1:
        return num
    return re_func(num,n-1)*10+num
def func(num,n):
#循环加法
    resurt = 0
    for i in range(1,n+1):
        resurt +=re_func(num,i)
    return resurt

while True:
    num1 = input("请输入数字1:\n")
    num2 = input("请输入数字2:\n")

    if(num1 == "退出" or num2 == "退出"):
        break
    try:
        num1_int = math.floor(eval(num1))
        num2_int = math.floor(eval(num2))
        print("结果为",func(num1_int,num2_int))
    except:
        print("输入错误")

          2.3 计算2-100之间素数的个数，返回结果

import  math

def is_func(n):
    if n < 2 :
        return "不是素数"
    if n == 2:
        return "是素数"
    for i in range(2,math.ceil(n**0.5)):
        if n % i == 0:
            return "不是素数"
    return "是素数"

def count_func(num):
    resurt = 0
    for i in range(num+1):
        if is_func(i) == "是素数":
            resurt += 1
    return resurt

while True:
    num = input("请输入数字:\n")
    if(num == "退出"):
        break
    try:
        num_int = math.floor(eval(num))
        print("2到{}素数的个数为{}".format(num,count_func(num_int)))
    except:
        print("输入错误")

          2.5 交换某两个变量的值

import math
def change_value(func):
    def inner(num1,num2):
        return func(num2,num1)
    return inner

@change_value
def func1(num_a,nun_b):
    return num_a,nun_b


while True:
    num_a = input("请输入数字1:\n")
    num_b = input("请输入数字2:\n")
    print("num_a={}，num_b={}".format(num_a,num_b))
    num_a,num_b=func1(num_a,num_b)
    print("交换后num_a={}，num_b={}".format(num_a, num_b))