Challenges
Reddit challenges in python language.
| Files | Code and Result |
|---|---|
challenge3_easy
''' Welcome to cipher day!
write a program that can encrypt texts with an alphabetical caesar cipher.
This cipher can ignore numbers, symbols, and whitespace.
for extra credit, add a "decrypt" function to your program!
Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Cipher: XYZABCDEFGHIJKLMNOPQRSTUVW
The encryption can also be represented using modular arithmetic
by first transforming the letters into numbers, according to the scheme,
A = 0, B = 1,..., Z = 25.[1] Encryption of a letter x by a shift n
can be described mathematically as,[2]
E_n(x) = (x + n) \mod {26}.
Decryption is performed similarly,
D_n(x) = (x - n) \mod {26}.
'''
''''
Decrypt
ABCDEFG...... to
XYZABCD......
'''
def encode(letter):
''' str -> str '''
alph = 'abcdefghijklmnopqrstuvwxyz'
indx = alph.index(letter)
shift = (indx - 3) % 26
result = alph[shift]
return result
if __name__ == '__main__':
out = ''
#message = 'retreat we are beat'
message ='retreat'
for letter in message:
if letter.isalpha():
out += encode(letter)
else:
out += ' '
print('Message is {0} and when encrypted it is {1}'.format(message, out))
ResultMessage is retreat and when encrypted it is obqobxq |