It looks like when you are adding sandpile 1 to sandpile 2, one of them is getting modified. The add method should return a new sandpile with the final value, while the original two sandpiles are left in their original state.

Either that, or you have something deeper that's wrong, such as sharing the data between two sandpiles. Basically, the test is checking to make sure the two sandpiles have the same values as they started with.

I agree, that string is valid, and the first non-repeating letter (meeting the challenge reqs) is p, which means it's valid.

However, that string also has several control characters (invisible in print), which are also duplicated. Those hidden characters could be confusing.

Approved! Thanks!

You're welcome, glad you enjoyed it!

Awesome! Thank you! I didn't feel comfortable approving my own kata—and I've been pretty busy over on the Qualified side for the last... uh, 5 years.

Correct

I don't think this is an issue with the kata, it may have been an old issue with the Codewars code runner.

I changed the title and made a note in the description. I don't want to invalidate existing solutions, and I don't think it's so confusing that it's worth modifying the kata to accept both the old and new solutions.

Read the description more carefully. It says:

• Make sure you decode the URI components correctly

You did not decode the URI components.

Fixed, thanks!

Neither number you mentioned is special. Neither 7540 nor 7541 are descending sequences.

The line from the instructions is (emphasis added):

The digits are sequential, decrementing: 4321

Great catch, St3f4n!