Not an issue --> Range for the random tests: 1000 <= n <= 200000

From PostgreSQL 14 documentation, 7.2.5:
Currently, window functions always require presorted data, and so the query output will be ordered according to one or another of the window functions' PARTITION BY/ORDER BY clauses. It is not recommended to rely on this, however. Use an explicit top-level ORDER BY clause if you want to be sure the results are sorted in a particular way.
https://www.postgresql.org/docs/14/queries-table-expressions.html

True, but that seems more of a problem with the Title method which is supposed to capitalize every word. I agree that it should be clarified in the description or the test cases if that's not OK.

https://oeis.org/A083876

What's interesting is that when I tried your solution, it timed out roughly half of the time. When it didn't time out, it passed the test suite in around 6 seconds. Is this a server fault or 'unlucky' test cases?

Pretty nice, thank you for new knowledge!

Same problem happened to me. Took 3 tries to pass the test using ROUND(numeric, int)::float

@raimiss8 I disagree with you. I recommend reading an article about it, written by Jon Skeet (a C# expert): http://jonskeet.uk/csharp/stringbuilder.html

And in JS, you don't want to implement a stack object from scratch anyway; just use arrays like any normal people do. It's also faster because you don't have to deal with bottlenecks handling objects (built-in in Python and JS are fast).

I don't think so, unless you're adding it as a secondary ORDER BY

And Arphox I think your solution is not that good to :) string builder is good choise only if strings are big or is many of them like milion or so. In this case Concat or string join something like this or even aggregate is better choise when building small string.

Yes this solution is not the best performance wise its jus simple one :)

Your random tests are vulnerable to input modification.

No it isn't. This one literally iterates through the string 6 times which is waste of CPU. Check my solution for a fast one (maybe the fastest).

Added that test to all languages. Marking your post as a Suggestion next time is a good idea.