1. 编写一个函数，求1+2+3+...+N

def my_sum(N):
    sum1 =0
    for num in range(1, N+1):
        sum1 += num
    print(sum1)

2. 编写一个函数，求多个数中的最大值

def max_num(*nums):
    max1 = 0
    for x in nums:
        if x > max1:
            max1 = x
    print(max1)

3. 编写一个函数，实现摇骰子的功能，打印n个骰子的点数和

import random
def shaizi_sum1(n):
    num1 = 0
    for x in range(n):
        num1 += random.randint(1, 6)
    print(num1)

方法二

from random import randint
def play_dice(n):
    sum1 = 0
    for _ in range(n):
        num = randint(1, 6)
        print(num)
        sum1 += num
    return sum1

4. 编写一个函数，交换指定字典的key和value。

#  如:{'a':1, 'b':2, 'c':3} ---> {1:'a', 2:'b', 3:'c'}
def change_key_value(dict1:dict):
    for key in dict1.copy:
        value = dict1[key]
        del dict1[key]
        dict1[value] = key

5. 编写一个函数，提取指定字符串中的所有的字母，然后拼接在一起后打印出来

#     如:'12a&bc12d--' ---> 打印'abcd'
def letter(str1):
    C = ''
    for x in str1:
        if 'a' < x < 'z' or 'A' < x < 'Z':
            C += x
    print(C)

方法二

def connet(str1:str):
    mstr = ''
    for char in str1:
        if char.isalpha():
            mstr += char
    return mstr

6. 写一个函数，求多个数的平均值

def avg(*nums):
    sum1 = sum(nums)
    avg = sum1/len(nums)
    print(int(avg))

7. 写一个函数，默认求10的阶层，也可以求其他数的阶层

def jie_cheng(num=10):
    sum1 = 1
    for x in range(1, num+1):
        sum1 *= x
    print(sum1)

8. 写一个函数，可以对多个数进行不同的运算

# 如: operation('+', 1, 2, 3) ---> 求 1+2+3的结果
# operation('-', 10, 9) ---> 求 10-9的结果
# operation('*', 2, 4, 8, 10) ---> 求 2*4*8*10的结果
def operation(str, *nums):
    num = 0
    for x in str:
        if x == '-':
            for y in nums:
                num -= y
            print(num)
        elif x == '+':
            num = 0
            for y in nums:
                num += y
            print(num)
        elif x == '*':
            num = 1
            for y in nums:
                num *= y
            print(num)
        else:
            x == '/'
            num = 1
            for y in nums:
                num /= y
            return num
print(operation('+', 2,5,6))

9.写一个函数，求指定列表中，指定的元素的个数

def num(list, n):
    print(list.count(n))

# 方法二
def nrj_count(list1,item):
    count = 0
    for x in list1:
        if x == item:
            count += 1
    return count

10.写一个函数，获取指定列表中指定元素对应的下标(如果有多个，一起返回)

def nrj_index(list1,item):
    indexs = []
    for index in list1[index]:
        x = list1[index]
        if x == item:
            indexs.append(index)
    return indexs