This was a pain - a beautiful, sensational type of pain.
THANK YOU!

How much of Combinatorics does this kata need? Like I guess around 30%-40% is all about combinatorics to find the numbers which contain "5" in them.

Changed!

Searching in-depth to find the optimal algorithm to pass and solve katas like this one is funny and rewarding.

.

Thanks for pointing that out!

It seems, my half-baked solution slipped through tests due to the fact that at that moment random tests was formed without any upper palindromic boundary values.
You can provide tests in which at least one of the boundariesis guaranteed to be a palindrome itself: (111, 2222), (123, 3333), (111, 2345) and nothing will accidentally slip through. )

Have test.assertEquals(no5s(16384, 32768), 0, 'a = 82, b = 43') in JS version again.

Haha, it's OK! It finally dawned on me what it was all about and I’ve already optimized even my final solution, but I won’t republish it - I’d rather celebrate it with a couple of glasses of cognac - no one can drink away the talent for being a little stupid! Cheers!

Thank you for completing my kata! I especially loved the process of creating this one.

Unfortunately I can't remove solutions, but I'm glad you submitted a final solution after debugging.

BTW, is it possible to remove the fisrt debug version of my solution

nope, sorry... ;)

Not easy but incredible fun - I couldn't asleep a couple of nights :D
Thanks for the great kata!
PS: BTW, is it possible to remove the fisrt debug version of my solution, that didn't pass all the tests and has been unecspectadly published by clicking on the button, that was changed from 'attempt' to 'submit' at that moment?

Great problem super tricky

There is something wrong with the test cases. It gives an output "a = -50029, b = 21093: expected 29800 to equal 11654", but in VS Code console.log() it is actually 29800. Could you please fix it.