刷题继续

大家好，我又回来了，昨天和大家分享了 31-40 题，今天继续来看 41~50 题

Question 41:

Write a program which can map() to make a list whose elements are square of elements in [1,2,3,4,5,6,7,8,9,10].

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解法一

lst=[i for i in range(1,11)]
lst_square = list(map(lambda x:x*x,lst))
print(lst_square)

解法二

li = [1,2,3,4,5,6,7,8,9,10]
squaredNumbers = map(lambda x: x**2, li) 
print(list(squaredNumbers))

Question 42:

Write a program which can map() and filter() to make a list whose elements are square of even number in [1,2,3,4,5,6,7,8,9,10].

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解法一

lst=[i for i in range(1,11)]
even_numbers = list(map(lambda x: x**2, filter(lambda x: x%2==0, lst)))
print(even_numbers)

解法二

def even(x):
    return x%2==0

def squer(x):
    return x*x

li = [1,2,3,4,5,6,7,8,9,10]
li = map(squer,filter(even,li))  
print(list(li))

Question 43:

Write a program which can filter() to make a list whose elements are even number between 1 and 20 (both included).

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解法一

even_numbers = list(filter(lambda x: x%2==0, range(1,21)))
print(even_numbers)

解法二

def even(x):
    return x%2==0

evenNumbers = filter(even, range(1,21))
print(list(evenNumbers))

Question 44:

Write a program which can map() to make a list whose elements are square of numbers between 1 and 20 (both included).

---

解法一

def sqr(x):
    return x*x

squaredNumbers = list(map(sqr, range(1,21)))
print (squaredNumbers)

解法二

squaredNumbers = list(map(lambda x: x**2, range(1,21)))
print(squaredNumbers)

Question 45:

Define a class named American which has a static method called printNationality.

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解法一

class American():
    @staticmethod
    def printNationality():
        print("I am American")

american = American()
american.printNationality()   # this will not run if @staticmethod does not decorates the function.Because the class has no instance.
                             

American.printNationality()   # this will run even though the @staticmethod does not decorate printNationality()                            

Question 46:

Define a class named American and its subclass NewYorker.

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解法一

class American():
    pass

class NewYorker(American):
    pass

american = American()
newyorker = NewYorker()

print(american)
print(newyorker)

Question 47:

Define a class named Circle which can be constructed by a radius. The Circle class has a method which can compute the area.

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解法一

class Circle:
    def __init__(self,radius):
        self.radius = radius
    def area(self):
        return (self.radius**2*3.14)

# Test
circle = Circle(5)
print(circle.area())

Question 48:

Define a class named Rectangle which can be constructed by a length and width. The Rectangle class has a method which can compute the area.

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解法一

class Rectangle():
    def __init__(self,l,w):
        self.length = l
        self.width = w

    def area(self):
        return self.length*self.width


rect = Rectangle(2,4)
print(rect.area())

Question 49:

Define a class named Shape and its subclass Square. The Square class has an init function which takes a length as argument. Both classes have a area function which can print the area of the shape where Shape’s area is 0 by default.

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解法一

class Shape():
    def __init__(self):
        pass

    def area(self):
        return 0

class Square(Shape):
    def __init__(self,length = 0):
        Shape.__init__(self)
        self.length = length

    def area(self):
        return self.length*self.length

Asqr = Square(5)
print(Asqr.area())      # prints 25 
print(Square().area())  # prints à

Question 50:

Please raise a RuntimeError exception.

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解法一

raise RuntimeError('something wrong')

源代码下载

这十道题的代码在我的 github 上，如果大家想看一下每道题的输出结果，可以点击以下链接下载：

• Python 41-50 题

我的运行环境 Python 3.6+, 如果你用的是 Python 2.7 版本，绝大多数不同就体现在以下 3 点：

• raw_input() 在 Python3 中是 input()
• print 需要加括号
• fstring 可以换成.format(), 或者 %s，%d

谢谢大家，我们下期见！希望各位朋友不要吝啬，把每道题的更高效的解法写在评论里，我们一起进步！！！