问题
I need to write a substitution cipher for the digits 0,1,2,3,...,9 substitutes each digit in 0,1,2,3,...,9. It can be represented as a 10 digit string specifying how each digit in 0,1,2,3,...,9 is substituted. For example, the 10 digit string '3941068257' specifies a substitution cipher in which digit 0 is substituted with digit 3, 1 with 9, 2 with 4, and so on. To encrypt a non negative integer, substitute each of it's digits with the digit specified by the encryption key. Implement function cipher() that takes as in put a 10 digit string key and a digit and a digit string (i.e., the clear text to be encrypted) and returns the encryption of the clear text.
>>>encrypt('3491068257', '132')
'914'
>>>encrypt('3491068257', '111')
'999'
Thank you for your help :)
回答1:
from string import maketrans
zero_through_nine = "".join(str(i) for i in range(10))
out_tab = "3491068257"
trantab = maketrans(zero_through_nine,out_tab )
print "111".translate(trantab)
hopefully you look into it to understand it....
回答2:
I would like to see an attempt out of the OP posted, but anyway
def encrypt(key,s):
return ''.join(key[int(c)] for c in s)
This uses each "key" in the string, and uses that to look up the appropriate character.
回答3:
In the encrypt function you could create a map of lookups using the first string parameter. Then go through each character in the second parameter string and use this map for substitution and create and return a new string
来源：https://stackoverflow.com/questions/15583375/python-substitution-cipher