Hi, Anton!

Are you sure there is definitely a case with empty input?

Well, I guess there's none of them - all the inputs do contain certain values.

A possible cause to your illustration may be input mutating (i.e. you don't make a copy of an input array, but change that in place).

That's a problem with your code, but let me figure out why.

100 million characters in 21 seconds is way too slow. The tests test 4/5 strings with 100 million characters and 1 string with 1 billion characters and it has to pass is 12 seconds. That is your solution should pass them in ~6 seconds max because the tests also need to create the huge strings and run the reference solution themselves, which takes a little bit less than half of the 12 seconds.

))

Wrong, your posts here are visible in the homepage when not marked as spoilers. There is no need to mark them all either, only when needed.

Please use spoiler flag next time.