面试题汇总(七)

1.这个程序的出的结果是class Singleton:    _instance = None    def __new__(cls,*args,**kwargs):        print(‘New‘)        if cls._instance is None:            print(‘Create‘)            cls._instance = super().__new__(cls,*args,**kwargs)        return cls._instance    def __init__(self):        print(‘Initialize‘)        self.prop = Nones1 = Singleton()s2 = Singleton()print(s1)print(s2)答案是: NewCreateInitializeNewInitialize<__main__.Singleton object at 0x00000202F3E70CC0><__main__.Singleton object at 0x00000202F3E70CC0>

python自带的数据类型有哪些?

答: 列表(list)    字符串(str)   元祖(tuple)   字典(dict)   集合(set)    布尔值(bool)

请用1行python代码实现1-1000之间整数的求和

print(sum(range(1,1001)))

请使用python递归实现n的阶乘

def myfac(n):    if n==1:       return 1    else:       return myfac(n-1)*nprint(myfac(5))

请使用python实现冒泡排序

bubble_sort(alist):    for j in range(len(alist) - 1, 0, -1):        # j表示每次遍历需要比较的次数，是逐渐减小的        for i in range(j):            if alist[i] > alist[i + 1]:                alist[i], alist[i + 1] = alist[i + 1], alist[i]li = [54, 26, 93, 17, 77, 31, 44, 55, 20]bubble_sort(li)print(li)

如何在linux下用一条命令,批量将某个目录下所有文件中指定字符串A(str A)转换为字符串B(str B)

不会

现有学生信息表student(字段项为stuld,stuName,class)和教师信息表teacher(字段项为teald,teaName,class),现虚查询每名教师(teaName)所教班级(class)数目及每个班级(class)中学生的数目,查询结果包含教师姓名(teaName),班级(class)和对应班级学生数目,请用一条sql语句实现

不会

请给出下短代码的执行结果

class B(object):    def fn(self):        print(B,‘fn‘)    def __init__(self):        print(B,‘INIT‘)class A(object):    def fn(self):        print(A,‘fn‘)    def __new__(cls,a):        print(a,‘NEW‘)        if a > 10:            return super(A,cls).__new__(cls)        return B()a1 = A(5)a1.fn()a2 = A(20)a2.fn()print(a1)print(a2)答案是5 NEW<class ‘__main__.B‘> INIT<class ‘__main__.B‘> fn20 NEW<class ‘__main__.A‘> fn<__main__.B object at 0x000001DF8A5A7128><__main__.A object at 0x000001DF8A58C748>

一个父类和子类,有初始化函数,有销毁函数,有子类继承父类的函数即可

class Father(object):    def __init__(self, age):        self.age = age        print("age: %d" % (self.age))?    def getAge(self):        print(‘父类的返回结果‘)        return self.age??class Son(Father):    def getAge(self):        print(‘子类的返回结果：‘)        return self.ageif __name__ == ‘__main__‘:    son = Son(18)    print(son.getAge())答案是：age: 18子类的返回结果：18

班级表class (id,name) 学生表 student (id,name,classid,score)

(1).写sql语句建表(2)写sql语句插入2个学生,2个班级(3)写sql语句,分组查询每个班级的平均分数,并按降序排序,输出,班级编号,班级名,平均分数

python自带的数据类型有哪些?

list, string, dict, tuple, set, boolean

请用一行python代码实现1--1000之间整数的求和.

print(sum(range(1001)))

请使用python递归实现n的阶乘.

def f(x):    if x == 1:    return 1else:    return f(x-1)*x a = input(‘请输入一个大于0的整数:’)print(f(a))

请用python实现冒泡排序

def bubble_sort(alist):    for j in range(len(alist)-1,0,-1):        for i in range(j):            if alist[i] > alist[i+1]:                alist[i], alist[i+1] = alist[i+1], alist[i]li = [54,26,93,17,77,31,44,55,20]bubble_sort(li)print(li)

请给出下面代码的执行结果

new 5B initB fnnew 20init 20A fn

如何在linux下用一条命令,批量将某目录下所有文件中指定字符串 A替换为字符串B?

sed -i "s/A/B/g" `grep A -rl D`   #百度的 看不懂

只能看清map 用法

def a(x):    return x**2print(map(a,[1,2,3,4]))#返回结果[1,4,9,16]

写一个父类和子类,有初始化函数,有销毁函数有子类继承父类的函数即可

class Father():    def __init__(self):        return ‘fathre’    def __del__(self):        return ‘father已经销毁’    class Son(Fathre):    def __init__(self):        return ‘son’    def __del__(self):        return ‘son已经销毁’

班级表 class(id,name)学生表student(id,name,class_id,score)

①写sql语句建表

②写sql语句加入2班级,2学生

③写sql语句,分组查询出每个班级的平均分数,并按降序排序,输出,班级编号,班级名,平均分数

①:CREATE TABLE IF NOT EXISTS class(id INT PRIMARY KEY AUTO_INCREMENT,NAME VARCHAR(50))CREATE TABLE student (  id VARBINARY(20),  NAME VARCHAR(50),  class_id INT,  score DOUBLE)?②:INSERT INTO class(NAME) VALUES(‘1803a‘);INSERT INTO class(NAME) VALUES(‘1804a‘);INSERT INTO student(id,NAME,class_id,score) VALUES(‘1001‘,‘张三‘,1,88.0);INSERT INTO student(id,NAME,class_id,score) VALUES(‘1001‘,‘李四‘,1,99.0); ③:SELECT s.class_id,c.`name`,s.scoFROM(SELECT class_id,AVG(score) scoFROM studentGROUP BY class_idORDER BY sco DESC)s JOIN class cON s.`class_id`=c.`id`

原文地址：https://www.cnblogs.com/cwx-0324/p/11393365.html