I've spent like 5+ hours trying to understand the editorial for this problem.

It seem's like the official editorial was not understandable in the first place?

The official editorial and jiangly's ac code is all I found.

Are there any other materials that presents this problem's solution?

I first learned C++ early last year, and now I'm almost red on Codeforces, with just about 4 months left until my first and only Korean Team Selection Contest for IOI.

As mentioned in the title, I don't really understand why I only perform well on Codeforces. Recently, I had a terrible performance on AtCoder arc181, and even a few months ago, my results in the Korean Olympiad in Informatics were far from what you'd expect from someone close to red.

I also tried reading through last year's Korean Team Selection Contest problems, but I couldn’t shake the feeling that I wouldn't be able to solve them. One of the participants in the contest, Kawaii2DIdolOfGSHS, solved incredibly difficult problems one of the problem if you are interested... during the competition and achieved a pretty good ranking.

I’ve also attempted solving JOI problems. Is it normal to take several days to solve one OI problem, even while referring to editorials? After trying a few problems, I gave up because the time and effort didn’t seem worth it.

With the Korean Team Selection Contest just around the corner, I’m not sure what to do. I’ve never performed well in any contests other than Codeforces, and I’m worried that I won’t do well in the upcoming contest.

Honestly, at this point, I’m pretty sure I won’t even make it into the top 10 if I participate in the Korean Team Selection Contest in my current state.

What is the best course of action I can take in the remaining 4 months to prepare for the Korean Team Selection Contest?

Summary : 1. I can't solve hard problems (especially OI style) 2. My performance is bad other than Codeforces. 3. How can I perform well in team selection contest?

I see some very good coders such as snuke, Petr do this. struct Solver and writing their actual solution in the Solver's method void solve(). Is there any practical benefit of doing this?