still a duplicate. We already have too much kata about collatz sequences.

• No sample tests;
• No random tests;
• The tests which should be really, like, time-efficient aren't present, so there are only trivial cases left.
• Probably the duplicate of the existing kata, but the condition whether x is repeating a number and in which position. is unique for now

Hi, sorry first time trying to publish something, getting used to the platform. It is fixed now.

Unpublishing for now. Please fix the kata and bring it to a publishable, runnable state.

Server Execution Error:
Failed to detect class name:
public boolean looping(10, 5);
public boolean looping(10, 7);
public boolean looping(0, 5);
public boolean looping(0, 1);
public boolean looping(100, 50);
public boolean looping(100, 7);
public boolean looping(13, 5);
public boolean looping(13, 15);
public boolean looping(17, 7);
Request Error:
Request failed with status code 422
Please fix the issue and try again.

Hi,

First of all you can solve this Kata with a simple loop that check whether the letter is uppercase (in which case you would add a space before it).
To your question, these are Regular expressions. Plainly speaking it is an easy way to find and manipulate patterns in a string.
The [A-Z] means any upper case character and $1 means the first group you found (so they add a space and $1).

Here is a website you could learn about the subject: https://www.vogella.com/tutorials/JavaRegularExpressions/article.html