Cyclic Sort Katas

Installation guide

Simply pull this repo and run

composer install

then run

phpunit

or if there is no phpunit install globally, run through the vendor directory

./vendor/phpunit/phpunit/phpunit

Problem Statement

/**
 * Cyclic sorts the input using the ordering.
 * @param string input  The input string value.
 * @param int ordering  The ordering, > 1.
 * @return  The reordered output
 */
function cyclicSort($input, $ordering) { }

Given an array with these items “A”, “B”, “C”, “D”, “E”, “F”, “G”, “H”, “I”, “J”; and the ordering of 7.

Counting from “A” and the 7th character is “G”.

So the first output character is “G”.

Remove “G” and remains “A”, “B”, “C”, “D”, “E”, “F”, “H”, “I”, “J”.

Then starting from “H”, count 7 in cyclic fashion (and roll over, starts from beginning), and reach “D”.

So the second output character is “D”.

Remove “D” and remains “A”, “B”, “C”, “E”, “F”, “H”, “I”, “J”.

Starting from “E” and count 7 in cyclic fashion (and roll over, starts from beginning) and reach “B”.

So the second output character is “B”.

Remove “B” and remains “A”, “C”, “E”, “F”, “H”, “I”, “J”.

Starting from “C” and count 7 and continue the process until nothing remains.

Finally, it should produce the output array of this order.

"G", "D", "B", "A", "C", "F", "J", "E", "H", "I"

$input = "ABCDEFGHIJ";
$output = cyclicSort($input, 7);
echo $output.PHP_EOL; // GDBACFJEHI

Tasks

1. What is the output of “0123456789ABCDEF”, if the order is “11”?

2. With the order is “13”, the sorted/scrambled message is given below:

d nntobmeanhnld ftcitao.Laluw lyteuhtoohevet iGa rs llUnai coBn o  oayg. p no .oddf .ityio gntire d. LoKrRiouyiG

What is the original message (before it was cyclically sorted)?