cryptosquare

Crypto Square

Implement the classic method for composing secret messages called a square code.

Write a program that, given an English text, outputs 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. Phrases that fill perfect squares (r X r) should be output in r-length chunks separated by spaces. Imperfect squares will have n empty spaces. Those spaces should be distributed evenly across the last n rows.

imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn sseoau

Notice that were we to stack these, we could visually decode the cyphertext back in to the original message:

imtgdvs
fearwer
mayoogo
anouuio
ntnnlvt
wttddes
aohghn
sseoau

To run the tests simply run the command go test in the exercise directory.

If the test suite contains benchmarks, you can run these with the -bench flag:

go test -bench .

For more detailed info about the Go track see the help page.

Source

J Dalbey's Programming Practice problems http://users.csc.calpoly.edu/~jdalbey/103/Projects/ProgrammingPractice.html

Submitting Incomplete Problems

It's possible to submit an incomplete solution so you can see how others have completed the exercise.