It doesn't modify the arrays, but creates a new array.

sorted will be delegeted to Arrays.sort() here
and Arrays.sort() is O(nlogn) which is more than
O(4n)

You can safely assume if it can be up to 2e6, it can be down to -2e6.

I am not really sure if size of regex is your problem here. My java solution uses kind-of-sounding-similar approach, and my longest expression is ~117kB (sic!) for 17. A couple of other expressions are also in area of a couple of tens of kilobytes.

My solution does not time out even though I do no particular simplification, I use capturing groups and backtracking quantifiers. It means, my expressions are TOTALLY not optimized, it;s maybe just the order of eliminated nodes what controls the size of my expressions. But in other languages, with other regex libraries, it could be necessary to optimize the expression a bit. AFAIK Python has a limit of number of capturing groups, and maybe you could use non-giving back quantifiers to reduce backtracking of the regex?

• first check that you don't use matching groups (even if you're not using python)
• second... I cannot really tell (cause I solved it building my reasonning from scratch), but since you mentionned this kind of concept, I'd begin by checking "reduction" algo of that kind of thing specifically.

Mentioned case-sensitivity in description

If you insert a letter, it implies that you have to delete and add a certain letter: (cost 2)
If you simply add or delete: (cost 1)
This is a well known approach called minimum edit distance.
I passed all tests but the one we are talking about.

e.g.
rkacypviuburk to zqdrhpviqslik, cost: 16 because you have to delete and add 8 letters
rkacypviuburk to karpscdigdvucfr, cost: 12 because you have to delete and insert 5 and also delete 2 letters

same account to the test you are addressing!

me too. damn!

See https://stackoverflow.com/questions/1247486/list-comprehension-vs-map
in this case map is best practice.

Of course C is also checking this "Low-ace straight", contradicting the instructions... edit: I mean in the sample tests, anyway. I don't get that far in real tests yet ;)

Oh damn... I fought n was the index in Fibonacci sequence.

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