from math import ceil, sqrt

import sys

if sys.version_info[0] == 2:

from itertools import izip_longest as zip_longest

else:

from itertools import zip_longest

def encode(msg):

msg = _cleanse(msg)

square_size = int(ceil(sqrt(len(msg))))

square = _chunks_of(msg, square_size)

return ' '.join([''.join(col)

for col in zip_longest(*square, fillvalue=' ')])

def _cleanse(s):

"""Lowercase a string and remove punctuation and whitespace

"""

return ''.join([c for c in s if c.isalnum()]).lower()

def _chunks_of(s, n):

if len(s) <= n:

return [s]

return [s[:n]] + _chunks_of(s[n:], n)