Crypto Square
Implement the classic method for composing secret messages called a square code.
Given an English text, output the encoded version of that text.
First, the input is normalized: the spaces and punctuation are removed
from the English text and the message is downcased.
Then, the normalized characters are broken into rows. These rows can be
regarded as forming a rectangle when printed with intervening newlines.
For example, the sentence
"If man was meant to stay on the ground, god would have given us roots."
is normalized to:
"ifmanwasmeanttostayonthegroundgodwouldhavegivenusroots"
The plaintext should be organized in to a rectangle. The size of the
rectangle (r x c
) should be decided by the length of the message,
such that c >= r
and c - r <= 1
, where c
is the number of columns
and r
is the number of rows.
Our normalized text is 54 characters long, dictating a rectangle with
c = 8
and r = 7
:
"ifmanwas" "meanttos" "tayonthe" "groundgo" "dwouldha" "vegivenu" "sroots "
The coded message is obtained by reading down the columns going left to
right.
The message above is coded as:
"imtgdvsfearwermayoogoanouuiontnnlvtwttddesaohghnsseoau"
Output the encoded text in chunks that fill perfect rectangles (r X c)
,
with c
chunks of r
length, separated by spaces. For phrases that are
n
characters short of the perfect rectangle, pad each of the last n
chunks with a single trailing space.
"imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn sseoau "
Notice that were we to stack these, we could visually decode the
ciphertext back in to the original message:
"imtgdvs" "fearwer" "mayoogo" "anouuio" "ntnnlvt" "wttddes" "aohghn " "sseoau "