mamboitaliano / exercism_cryptosquare_js

Javascript practice with the CryptoSquare problem from Exercism

Crypto Square

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

The input is first 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 54 characters long.

Broken into 8-character columns, it yields 7 rows.

Those 7 rows produce this rectangle when printed one per line:

ifmanwas
meanttos
tayonthe
groundgo
dwouldha
vegivenu
sroots

The coded message is obtained by reading down the columns going left to right.

For example, the message above is coded as:

imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn sseoau

Write a program that, given an English text, outputs the encoded version of that text.

The size of the square (number of columns) should be decided by the length of the message.

If the message is a length that creates a perfect square (e.g. 4, 9, 16, 25, 36, etc), use that number of columns.

If the message doesn't fit neatly into a square, choose the number of columns that corresponds to the smallest square that is larger than the number of characters in the message.

For example, a message 4 characters long should use a 2 x 2 square. A message that is 81 characters long would use a square that is 9 columns wide.

A message between 5 and 8 characters long should use a rectangle 3 characters wide.

Output the encoded text grouped by column.

For example:

• "Have a nice day. Feed the dog & chill out!"
  • Normalizes to: "haveanicedayfeedthedogchillout"
  • Which has length: 30
  • And splits into 5 6-character rows:
    • "havean"
    • "iceday"
    • "feedth"
    • "edogch"
    • "illout"
  • Which yields a ciphertext beginning: "hifei acedl v…"

Setup

Go through the setup instructions for JavaScript to install the necessary dependencies:

http://exercism.io/languages/javascript

Making the Test Suite Pass

Execute the tests with:

$ jasmine-node .

In many test suites all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by changing xit to it.

Source

J Dalbey's Programming Practice problems view source