练习

练习描述

1.计算1-100所有的数之和
2.判断列表中数字2出现的次数  
 l1 = [11,2,3,2,2,1,2,1,2,3,2,3,2,3,4,3,2,3,2,2,2,2,3,2]
3.编写代码自动生成所有页网址(注意总共多少页)
	https://movie.douban.com/top250
4.编写代码打印出下列图形(ps:for循环嵌套)  
*****  
*****  
*****  
*****

题解

'''练习1'''
dll = 0
for i in range(1, 101):
    dll += i
print(dll)  # 5050
print(sum(range(1, 101)))  # 5050

'''练习2'''
l1 = [11, 2, 3, 2, 2, 1, 2, 1, 2, 3, 2, 3, 2, 3, 4, 3, 2, 3, 2, 2, 2, 2, 3, 2]
count = 0
for i in l1:
    if i == 2:
        count += 1
print(count)  # 13

'''练习3'''
for i in range(1, 251):
    print('https://movie.douban.com/top%s' % (i,))  # 输出250个网页
	
# 输出豆瓣top250
start_value = 0
page_num = 10
for _ in range(page_num):
    url = f'https://movie.douban.com/top250?start={start_value}'
    start_value += 25
    print(url)

'''练习4'''
for _ in range(4):  
    for j in range(5):
        print('*', end='')
    print()

for i in range(4):
    print("*****")