Question

Have you ever dreamed of being a spy? Well here's your chance! We need you to decode some coded messages.

The code is fairly simple – you just need to select every third letter out of a sentence (starting from the first letter), and print out those letters with spaces in between them.

So the program should look like this:

Message? cxohawalkldflghemwnsegfaeap
c h a l l e n g e
​
or like this

Message? pbaynatnahproarnsm
p y t h o n

Answer 1

Here’s a simple Python solution that takes the message and prints every 3rd character (starting from the first) with spaces between them:

s = input("Message? ")
print(' '.join(s[::3]))

If you want to ignore non-letters (so spaces/punctuation aren’t counted), filter first:

s = input("Message? ")
letters = ''.join(ch for ch in s if ch.isalpha())
print(' '.join(letters[::3]))

Example:
Message? pbaynatnahproarnsm
p y t h o n