上次作业答案和找规律问题

# 1,print the largest prime number less than 100

for a in range(100,1,-1):
    b=1
    for x in range(2,a):
        if a%x==0:
            b=0
            break
    if b==1:
        print(a)
        break

# 2,output all prime number from 200 to 300

for a in range(200,301):
    b=1
    for x in range(2,a):
        if a%x==0:
            b=0
            break
    if b==1:
        print(a,'is a prime number')

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'''
*
**
***
****
*****
'''

for x in range(5):  # row
    s = ''
    for y in range(x+1):  # col 
        s+='*'
    print(s)
    
    

再来一道

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'''
****
***
**
*
'''

for x in range(4):  # row
    s = ''
    for y in range(4-x):  # col 
        s+='*'
    print(s)

#x 0 1 2 3 
#a 4 3 2 1  

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'''
a + x=4
a = 4-x

1+2=3
1 = 3-2
'''

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