【python入门】python基础13——基础练习题

时间:2023-02-22 23:59:00

练习一:

1,2,3,4,组成的互不相同的3位数有多少个

解:

python中是没有&&及||这两个运算符的,取而代之的是英文and和or。其他运算符没有变动。

python不支持类似 x++ 或 x-- 这样的前置/后置自增/自减运算符,因此只能用 += 或 -= 这种。

list = {1,2,3,4}
cnt = 0
for i in list:
    for j in list:
        for k in list:
            if i!=j and i!=k and j!=k:
                cnt+=1
print(cnt)

排序

x = int(input('x= '))
y = int(input('y= '))
z = int(input('z= '))
list=[]
list.append(x)
list.append(y)
list.append(z)
list.sort()
#list.sort(reverse = False)
for i in list:
    print(i)

时间:sleep 1s

import time
print( time.strftime('%Y-%m-%d %H:%M:%S',time.localtime()))
time.sleep(1)
print( time.strftime('%Y-%m-%d %H:%M:%S',time.localtime()))

递归:

#递归求5!
def func(n):
    if n==0:
        return 1
    return n*func(n-1)


for i in range(10):
    print(i,'!=',func(i))


buf = 'abcdef'
递归打印逆序字符串
def print_buf(a,l):
    if l == 0:
        return
    print(a[l-1])
    return print_buf(a,l-1)
print_buf(buf,len(buf))

join

#用逗号分隔开来,连接字符串
list = ['123','456','789']

s = ' '.join(str(i) for i in list)
s

range()

a,b = b,a

#调换位置 不需要像c一样用一个temp交换
list = [1,2,3,4,5]
for i in range(0,int(len(list)/2),1):
    list[i],list[len(list)-1-i] = list[len(list)-1-i],list[i]
print(list)


list 

for  i in range():

    for  j in range():

        x[i][j] = ...

#矩阵加法 
X = [[1,2,3],
     [4,5,6],
     [7,8,9]
    ]
Y = [[10,2,3],
     [4,50,6],
     [7,8,90]
    ]
Z = [[0,0,0],
     [0,0,0],
     [0,0,0]
    ]
for i in range(3):
    for j in range(3):
        Z[i][j] = X[i][j] + Y[i][j]
for z in Z:
    print (z)

匿名函数

sum_value = lambda x,y:x+y
print (sum_value(1,2))

(七)查找字符串的位置

s1 = 'asdffgdhfdjhgj'
s2 = 'ffg'
print (s1.find(s2))

(八)在字典中找到年龄最大的人,并输出

people = {'laowang':40,'tangyudi':30,'zhangsan':45}
m = 'tangyudi'
for key in people.keys():
    if people[m] < people[key]:
        m = key
print (m,people[m])
        
(九)列表转换为字典
k = ['tang','yudi']
v = [123,456]
print (dict([k,v]))

(十)从键盘输入一个字符串,将小写字母全部转换成大写字母,然后输出到一个磁盘文件"test"中保存

f = open('test.txt','w')
s = input('输入一个串串')
s = s.upper()
f.write(s)
f.close()

f = open('test.txt','r')
print (f.read())
f.close()