要求：在不增加或修改任何print语句，且函数内只能增加一条语句的情况下，输出："eric"。

1）只能修改f1()函数情况下，完成上述要求

name = 'lzl'
def f1():
    name = 'eric'
    print(name)
def f2():
    name = 'eric'
    f1()
f2()

2）只能修改f2()函数情况下，完成上述要求

name = 'lzl'
def f1():
    print(name)
def f2():
    global name
    name = 'eric'
    f1()
f2()

2.验证哥德巴赫猜想：（输入任意大于2的偶数，找出两个素数，其和等于输入的偶数。若找到输出这两个素数，否则输出找不到）这个问题可分解成两个步骤：1)判断正整数是否为素数，2)任意偶数是否能分解为两个素数之和。

def isPrime(q):
    if q <=1 :
        return False
    for i in range(2,q//2 + 1):
        if q % i == 0:
            return False
    return True
def createPrime(n):
    result = []
    for i in range(2,n+1):
        if isPrime(i):
            result.append(i)
    return result
n = 10
result = createPrime(n)
for i in result:
    for j in result:
        if i + j == n:
            print(i,j)

3.递归、递推、lambda函数。题目：计算表达式 ，x由用户通过键盘输入，要求精确到10-7，即数列和的最后一项的绝对值小于等于10-7为止。 。

递归

i = -1
n = 1
def power(n,x):
    global i
    print(i)
    i += 1
    if 1/(n ** x) > 1e-7 and i %2 == 0:
        return power(n+1,x) + 1/(n ** x)
    elif 1/(n ** x) > 1e-7 and i %2 != 0:
        return power(n+1, x) - 1/(n ** x)
    else:
        return 1/(n ** x)
x = int(input('输入x：'))
result = power(n,x)
print(result)

递推
def power(n,x):
    result = 0
    i = 0
    while 1/(n ** x) > 1e-7:
        if i %2 == 0:
            i+= 1
            result += 1/(n ** x)
        else:
            i+=1
            result -= 1/(n ** x)
        n += 1
    return result
n = 1
x = int(input('输入x：'))
result = power(n,x)
print(result)

# Lambda
x = int(input('输入x：'))
n = 1
result = map(lambda n,y=0: y +((-1) ** (n+1)) * (1 / (n ** x)) if float(1/(n ** x)) > 1e-7 else 0, range(1,10000))
print(sum(result))

4.题目：输入字符串26个英文字母，围成一圈，以字母a为1，依顺时针方向计数数到5的倍数时，将对应的字母划去，直到所有字母都被划去时为止。思路：可用列表实现或直接用字符串切片实现

s = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
point =0
number = 1
while len(s) > 1:
    if(number % 5 == 0):
        print(s[point])
        s.remove(s[point])
        point -=1
        number = 0
    point +=1
    number +=1
    if point > len(s) - 1:
        point = 0
print(s[0])

5.杨辉三角形

trangle = []
for i in range(1,9):
    if i == 1:
        list0 = [1]
    elif i == 2:
        list0 = [1,1]
    else:
        list0 = [1] * i
        for j in range(1,i-1):
            list0[j] = trangle[-1][j-1] + trangle[-1][j]
    trangle.append(list0)
for  i in  trangle:
    print(i)

6.题目：分类统计字符出现的次数（用字典统计）要求：

1）输入一串字符，统计并输出字符串中各字符出现的次数。

2）分类：字母letter，空格space，数字digit，其它字符other（用字典输出）。

# 频数统计
s = 'dgfrevgfdkgdsjgringvckghiregkjfdhgierghjkdfng'
count_dict = {}
for i in s:
    if i  not in count_dict.keys():
        count_dict[i] = 1
    else:
        count_dict[i] += 1
print(count_dict.items())

# 分类统计
s = 'sdfg343dgfd  345fg 6sdf4!$ @#$!'
count_dict = {'字母': 0, '空格': 0, '数字': 0, '其他字符': 0, }
for i in s:
    if i.isalpha():
        count_dict['字母'] += 1
    elif i.isspace():
        count_dict['空格'] += 1
    elif i.isdigit():
        count_dict['数字'] += 1
    else:
        count_dict['其他字符'] += 1
print(count_dict.items())

7.凯撒密码

import random
#生成10位随机字符串
def createStr():
    STR = [chr(i) for i in range(65,91)] #对应字符A-Z
    sa = ''
    for i in range (10):
        sa+=random.choice(STR)
    print(sa)
    return sa
#对字符串进行加密
def enCaesar(sa):
    sa_enCaesar = ''
    for i in sa:
        if ord(i) < 91 - k:
            sa_enCaesar += chr(ord(i) + k)
        else:
            sa_enCaesar += chr(ord(i) + k -26)
    return sa_enCaesar
#写入txt
def writeFile(sa_enCaesar):
    with open('加密.txt','w',encoding='utf-8') as f:
        f.write(sa_enCaesar)
#读取txt
def readFile():
    with open('加密.txt','r',encoding='utf-8') as e:
        sa = e.readline()
    return sa
#解密
def deCaesar(sa):
    sa_deCaesar = ''
    for i in sa:
        if ord(i) >= 65+k:
            sa_deCaesar += chr(ord(i) - k)
        else:
            sa_deCaesar += chr(ord(i) + 26 -k)
    return sa_deCaesar


sa = createStr()
k = int(input('请输入位移值：'))
sa_enCaesar = enCaesar(sa)
print('加密后：')
print(sa_enCaesar)
writeFile(sa_enCaesar)
sa = readFile()
sa_deCaesar = deCaesar(sa)
print('解密后：')
print(sa_deCaesar)