2018-05-22 10,961 views 评论

《Python语言程序设计基础》课后习题程序整理（第5~7章）

程序大多数为自己编写，程序可能不是最优，复杂度不是最好，也有可能存在理解错题意的问题，敬请谅解。

习题内容为高等教育出版社出版的由嵩天教授等编写的《Python语言程序设计基础（第2版）》中的习题内容。

第五章函数和代码复用

5.2 实现isOdd()函数，参数为整数，如果整数为奇数，返回True，否则返回False。

5.3 实现isNum()函数，参数为一个字符串，如果这个字符串属于整数、浮点数或复数的表示，则返回True，否则返回False。

def isNum(num):

if num.isnumeric():

return True

#下面为判断是否为复数的一种方法

elif len(num)==len(set(num)):

return True

else:

return False

&amp;nbsp;

num = input(&quot;请输入字符串：&quot;)

isnum = isNum(num)

if isnum:

print(&quot;你输入的字符串是数字！&quot;)

else:

print(&quot;你输入的字符串不是数字！&quot;)

&lt;strong&gt;5.4 实现multi()函数，参数个数不限，返回所有参数的乘积。&lt;/strong&gt;

def multi(nums):

'''

计算传入数字之积

'''

m=1

for i in nums:

m=m*i

return m

&amp;nbsp;

item_num1 = input(&quot;请输入数字，以空格分隔，若输入完成请按回车：&quot;)

item_num = item_num1.split(' ')

ls =[]

for i in item_num:

i = eval(i)

ls.append(i)

ans = multi(ls)

print(ans)

def isNum(num):

if num.isnumeric():

return True

#下面为判断是否为复数的一种方法

elif len(num)==len(set(num)):

return True

else:

return False

&nbsp;

num = input("请输入字符串：")

isnum = isNum(num)

if isnum:

print("你输入的字符串是数字！")

else:

print("你输入的字符串不是数字！")

<strong>5.4 实现multi()函数，参数个数不限，返回所有参数的乘积。</strong>

def multi(nums):

'''

计算传入数字之积

'''

m=1

for i in nums:

m=m*i

return m

&nbsp;

item_num1 = input("请输入数字，以空格分隔，若输入完成请按回车：")

item_num = item_num1.split(' ')

ls =[]

for i in item_num:

i = eval(i)

ls.append(i)

ans = multi(ls)

print(ans)

5.5 实现isPrime()函数，参数为整数，要有异常处理。如果整数是质数，返回True，否则返回False。

集中实现以上5.2、5.5的代码：

def isOdd(num):

'''

判断num数字是否是奇数，若是返回True，否则返回False

'''

if num%2 ==1:

return True

else:

return False

&amp;nbsp;

def isPrime(num):

'''

判断是否是质数，若是则返回True，否则返回False

'''

if num ==1:

return False

elif num ==2 or num ==3:

return True

else:

for i in range(3,num):

if(num%i == 0):

return False

return True

&amp;nbsp;

&amp;nbsp;

def switFunction(item,num):

'''

选择所需要的功能并输出结果

'''

if(item == 1):

ans = isOdd(num)

if ans:

print(&quot;{}是奇数&quot;.format(num))

else:

print(&quot;{}不是奇数&quot;.format(num))

if(item == 2):

ans = isPrime(num)

if ans:

print(&quot;{}是质数&quot;.format(num))

else:

print(&quot;{}不是质数&quot;.format(num))

if(item!=1 and item!=2):

print(&quot;请选择正确的功能&quot;)

&amp;nbsp;

func_num = input(&quot;请选择你所需要的功能，1为判断奇数，2为判断质数:&quot;)

func_num = eval(func_num)

item_num = input(&quot;请输入你需要判断的数字:&quot;)

item_num = eval(item_num)

switFunction(func_num,item_num)

&lt;strong&gt;5.7 汉诺塔问题。采用递归方法解决汉诺塔问题，要求输入汉诺塔的层数，输出整个移动流程。&lt;/strong&gt;

def move(n,a,b,c):

if n==1:

print(a,'--&amp;gt;',c)

else:

move(n-1,a,c,b)   #将前n-1个盘子从a移动到b上

move(1,a,b,c)     #将最底下的最后一个盘子从a移动到c上

move(n-1,b,a,c)   #将b上的n-1个盘子移动到c上

move(3,'A','B','C')

100

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112

113

def isOdd(num):

'''

判断num数字是否是奇数，若是返回True，否则返回False

'''

if num%2 ==1:

return True

else:

return False

&nbsp;

def isPrime(num):

'''

判断是否是质数，若是则返回True，否则返回False

'''

if num ==1:

return False

elif num ==2 or num ==3:

return True

else:

for i in range(3,num):

if(num%i == 0):

return False

return True

&nbsp;

def switFunction(item,num):

'''

选择所需要的功能并输出结果

'''

if(item == 1):

ans = isOdd(num)

if ans:

print("{}是奇数".format(num))

else:

print("{}不是奇数".format(num))

if(item == 2):

ans = isPrime(num)

if ans:

print("{}是质数".format(num))

else:

print("{}不是质数".format(num))

if(item!=1 and item!=2):

print("请选择正确的功能")

&nbsp;

func_num = input("请选择你所需要的功能，1为判断奇数，2为判断质数:")

func_num = eval(func_num)

item_num = input("请输入你需要判断的数字:")

item_num = eval(item_num)

switFunction(func_num,item_num)

<strong>5.7 汉诺塔问题。采用递归方法解决汉诺塔问题，要求输入汉诺塔的层数，输出整个移动流程。</strong>

def move(n,a,b,c):

if n==1:

print(a,'--&gt;',c)

else:

move(n-1,a,c,b) #将前n-1个盘子从a移动到b上

move(1,a,b,c) #将最底下的最后一个盘子从a移动到c上

move(n-1,b,a,c) #将b上的n-1个盘子移动到c上

move(3,'A','B','C')

第六章组合数据类型

6.1 随机密码生成。编写程序，在26个字母大小写和9个数字组成的列表中随机生成10个8位密码。

#6.1 random password

from random import choice

def rand_pass(N):

ls = []#create list

#add alpha and number into list

for i in range(97,123):

ls.append(chr(i))

for i in range(65,91):

ls.append(chr(i))

for i in range(48,58):

ls.append(chr(i))

#build one password

return ''.join(choice(ls) for i in range(N))

#produce ten passwords

for i in range(10):

ans_ls = rand_pass(8)

print(ans_ls)

#6.1 random password

from random import choice

def rand_pass(N):

ls = []#create list

#add alpha and number into list

for i in range(97,123):

ls.append(chr(i))

for i in range(65,91):

ls.append(chr(i))

for i in range(48,58):

ls.append(chr(i))

#build one password

return ''.join(choice(ls) for i in range(N))

#produce ten passwords

for i in range(10):

ans_ls = rand_pass(8)

print(ans_ls)

6.2 重复元素判定。编写一个函数，接受列表作为参数，如果一个元素在列表中出现了不止一次，则返回True，但不要改变原来列表的值。同时编写调用这个函数和测试结果的程序。

6.3 利用集合的无重复性改编程序练习题6.2的程序，获得一个更快更简洁的版本。

6.2/6.3代码如下：

def repDetermination_1(ls):

'''

Determinant of repeated elements.

If a list has repeated elements, return True.

If it does not has, return False

This is the Method ONE.

'''

for i in range(len(ls)):

for j in range(i+1,len(ls)):

if ls[i] == ls[j]:

return True

return False

&amp;nbsp;

def repDetermination_2(ls):

'''

Determinant of repeated elements.

If a list has repeated elements, return True.

If it does not has, return False

This is the Method TWO.

'''

len_or = len(ls)# original list

ls_set = len(set(ls))#after being a set

#if the original list has repeated elements, the length will be different

if len_or == ls_set:

return False

else:

return True

&amp;nbsp;

ls = input(&quot;请输入元素，以空格分隔。输入完毕，请按回车：\n&quot;)

ls = ls.split(&quot; &quot;)

ans_1 = repDetermination_1(ls)

ans_2 = repDetermination_2(ls)

print(&quot;方法一得到的结果是{}；\n方法二得到的结果是：{}&quot;.format(ans_1,ans_2))

def repDetermination_1(ls):

'''

Determinant of repeated elements.

If a list has repeated elements, return True.

If it does not has, return False

This is the Method ONE.

'''

for i in range(len(ls)):

for j in range(i+1,len(ls)):

if ls[i] == ls[j]:

return True

return False

&nbsp;

def repDetermination_2(ls):

'''

Determinant of repeated elements.

If a list has repeated elements, return True.

If it does not has, return False

This is the Method TWO.

'''

len_or = len(ls)# original list

ls_set = len(set(ls))#after being a set

#if the original list has repeated elements, the length will be different

if len_or == ls_set:

return False

else:

return True

&nbsp;

ls = input("请输入元素，以空格分隔。输入完毕，请按回车：\n")

ls = ls.split(" ")

ans_1 = repDetermination_1(ls)

ans_2 = repDetermination_2(ls)

print("方法一得到的结果是{}；\n方法二得到的结果是：{}".format(ans_1,ans_2))

6.5 生日悖论分析。生日悖论指如果一个房间里有23人或以上，那么至少有两个人生日相同的概率大于50%。编写程序，输出在不同随机样本数量下，23个人中至少两个人生日相同的概率。

import random

&amp;nbsp;

def generate_birthday(stu_nums):

'''

Generate the birthday of 23 students.

'''

birth_date= []

for i in range(stu_nums):

birth_date.append(random.randint(1,365))

return birth_date

&amp;nbsp;

def equal_birthday(birth_date):

x = birth_date[:]

x.sort()

for i in range(len(x)-1):

if x[i] == x[i+1]:

return True

return False

&amp;nbsp;

def birth_count(samples, stu_nums):

count = 0

m = []

for i in range(samples):

m = generate_birthday(stu_nums)

if equal_birthday(m):

count +=1

return count

&amp;nbsp;

samples = input(&quot;请输入样本数：\n&quot;)

samples = eval(samples)

stu_nums = 0

while(stu_nums &amp;lt;23):

stu_nums = input(&quot;请输入人数，不得小于23，默认为23：\n&quot;)

stu_nums = eval(stu_nums)

count = birth_count(samples,stu_nums)

rate = count/samples*100

print(&quot;概率为{:.2f}%&quot;.format(rate))

import random

&nbsp;

def generate_birthday(stu_nums):

'''

Generate the birthday of 23 students.

'''

birth_date= []

for i in range(stu_nums):

birth_date.append(random.randint(1,365))

return birth_date

&nbsp;

def equal_birthday(birth_date):

x = birth_date[:]

x.sort()

for i in range(len(x)-1):

if x[i] == x[i+1]:

return True

return False

&nbsp;

def birth_count(samples, stu_nums):

count = 0

m = []

for i in range(samples):

m = generate_birthday(stu_nums)

if equal_birthday(m):

count +=1

return count

&nbsp;

samples = input("请输入样本数：\n")

samples = eval(samples)

stu_nums = 0

while(stu_nums &lt;23):

stu_nums = input("请输入人数，不得小于23，默认为23：\n")

stu_nums = eval(stu_nums)

count = birth_count(samples,stu_nums)

rate = count/samples*100

print("概率为{:.2f}%".format(rate))

第七章：文件和数据格式化

7.1 Python源文件改写。编写一个程序，读取一个Python源程序文件，将文件中所有除保留字外的小写字母换成大写字母，生成后的文件要能够被Python解释器正确执行。

import keyword

&amp;nbsp;

excludes = keyword.kwlist

exclud = ['print','format']

fname = input(&quot;请输入要打开的文件（包含后缀名）：\n&quot;)

f = open(fname,'r').readlines()

print(f)

ls = []

for i in f:

i = i.split(&quot; &quot;)

ls.append(i)

&amp;nbsp;

print(ls)

#建立一个每行所有单词为一个元素的列表

new_name = input(&quot;请输入新建的文件的文件名（包含后缀名）：\n&quot;)

fo = open(new_name,'w+')

for i in range(len(ls)):

if f[i].isspace():

fo.write(&quot; &quot;)

for j in range(len(ls[i])):

x = ls[i][j]

if x in excludes:

x = x.lower()

else:

x = x.upper()

if x ==ls[i][len(ls[i])-1]:

fo.write(x +&quot;\n&quot;)

else:

fo.write(x+&quot; &quot;)

fo.close()

print(&quot;处理结束！&quot;)

import keyword

&nbsp;

excludes = keyword.kwlist

exclud = ['print','format']

fname = input("请输入要打开的文件（包含后缀名）：\n")

f = open(fname,'r').readlines()

print(f)

ls = []

for i in f:

i = i.split(" ")

ls.append(i)

&nbsp;

print(ls)

#建立一个每行所有单词为一个元素的列表

new_name = input("请输入新建的文件的文件名（包含后缀名）：\n")

fo = open(new_name,'w+')

for i in range(len(ls)):

if f[i].isspace():

fo.write(" ")

for j in range(len(ls[i])):

x = ls[i][j]

if x in excludes:

x = x.lower()

else:

x = x.upper()

if x ==ls[i][len(ls[i])-1]:

fo.write(x +"\n")

else:

fo.write(x+" ")

fo.close()

print("处理结束！")

程序仍然存在问题，例如range或者print因为和其它字符组成一个字符串，暂时想不到如何分割然后让其仍然小写。

7.2 图像文件压缩。使用PIL库对图片进行等比例压缩，无论压缩前文件大小如何，压缩后文件小于10KB。

from PIL import Image

def resizeImg(ori_name, des_name, dst_w, dst_h, save_q):

im = Image.open(ori_name)

ori_w,ori_h = im.size

widthRatio = heightRatio = None

ratio = 1

if(ori_w and ori_w&amp;gt;dst_w) or (ori_h and ori_h &amp;gt;dst_h):

if dst_w and ori_w&amp;gt;dst_w:

widthRatio = float(dst_w/ori_w)

if dst_h and ori_h&amp;gt;dst_h:

heightRatio = float(dst_h/ori_h)

&amp;nbsp;

if widthRatio and heightRatio:

if heightRatio &amp;lt; widthRatio:

ratio = heightRatio

else:

ratio = widthRatio

if widthRatio and not heightRatio:

ratio = widthRatio

if heightRatio and not widthRatio:

ratio = heightRatio

newWidth = int(ori_w *ratio)

newHeight = int(ori_h *ratio)

else:

newWidth = ori_w

newHeight = ori_h

&amp;nbsp;

im.resize((newWidth,newHeight),Image.ANTIALIAS).save(des_name, quality=save_q)

&amp;nbsp;

ori_name = '1.jpg'

des_name = '1_modify.jpg'

dst_w = 300

dst_h = 300

save_q = 50

resizeImg(ori_name, des_name, dst_w, dst_h, save_q)