Well I dont think so, in practice section filter to 5kyu and sorted by 'Popularity', you can see easier 5kyu katas there.

Could someone give me some random test examples? I pass all tests, but in Random I failed :(

There is no answer to optimize the code in general. We don't know what you are trying to do.

Could someone give any ideas to optimize the Python code?

It's not that easy. I advice you to practice on some easier katas involving regular expression. I believe this kata is not easy (I don't really know, I didn't solve it).

I wrote this expression at the beginning of my regex pattern, but it doesn't help me

^$

I wrote a fork for the Python translation that addresses this oversight (Kata author is inactive).

You just need to understand the basic arithmetics concepts of the description. If you are not familiar with it, make researches online, it's easy to find many resources related to it. I believe this is an easy 5 kyu kata and any hint would give away too much of the solution.

Hello everybody! Could someone give me idea, how to solve this kata. Now I'm stacked....

Stuck at 34...

Even the spaces count, try to reduce every unnecessary spaces. Also search code golfing. That gave me the final push :)

mention code golf in the title

AND

allow a few more characters to allow some variation