# 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`:

```text
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:

```text
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.

```text
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:

```text
imtgdvs
fearwer
mayoogo
anouuio
ntnnlvt
wttddes
aohghn
sseoau
```

## Setup

Check out [Exercism Help](http://exercism.io/languages/lisp) for instructions to
get started writing Common Lisp. That page will explain how to install and setup
a Lisp implementation and how to run the tests.

## Formatting

While Common Lisp doesn't care about indentation and layout of code,
nor whether you use spaces or tabs, this is an important consideration
for submissions to exercism.io. Excercism.io's code widget cannot
handle mixing of tab and space characters well so using only spaces is recommended to make
the code more readable to the human reviewers. Please review your
editors settings on how to accomplish this. Below are instructions for
popular editors for Common Lisp.

### VIM

Use the following commands to ensure VIM uses only spaces for
indentation:

```vimscript
:set tabstop=2
:set shiftwidth=2
:set expandtab
```

(or as a oneliner `:set tabstop=2 shiftwidth=2 expandtab`). This can
be added to your `~/.vimrc` file to use it all the time.

### Emacs

Emacs is very well suited for editing Common Lisp and has many
powerful add-on packages available. The only thing that one needs to
do with a stock emacs to make it work well with exercism.io is to
evaluate the following code:

`(setq indent-tab-mode nil)`

This can be placed in your `~/.emacs` (or `~/.emacs.d/init.el`) in
order to have it set whenever Emacs is launched.

One suggested add-on for Emacs and Common Lisp is
[SLIME](https://github.com/slime/slime) which offers tight integration
with the REPL; making iterative coding and testing very easy.

## Source

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

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