Hello, Codeforces!

Welcome to my blog about Codeforces Round 1123 (Div. 2)!

Date: September 25, 2026 Start time: 19:35 (UTC+5)

I decided to write this blog to share my experience, thoughts, and solutions from the contest. I will try to explain the problems in a simple and understandable way, focusing not only on the final solution but also on the ideas and observations that lead to it.

What to Expect

In this blog, I will go through the problems one by one, starting from the easiest tasks and gradually moving toward the more difficult ones.

For each problem, I plan to include:

The main observation How to think about the problem The key idea behind the solution The algorithm Time and memory complexity A C++ implementation Some additional notes and common mistakes

My goal is not simply to provide code. I want the explanations to show why the solution works, because understanding the idea is much more useful than memorizing an implementation.

Contest Strategy

One thing I always try to remember during a Codeforces contest is that getting stuck on one problem for too long can be dangerous.

If a problem seems difficult, it is often better to:

Read the statement carefully. Look for small examples. Try to find a simpler version of the problem. Identify patterns or useful observations. If nothing works, move on and return later.

Sometimes the solution appears immediately after coming back to a problem with a fresh perspective.

Let's Begin

I will try to keep the explanations beginner-friendly while still including the important details needed to understand the algorithms properly.

If you are reading this after the contest, I hope this blog helps you understand the problems you struggled with during the round.

And if you participated in the contest, feel free to share your approach or point out alternative solutions in the comments. Different approaches to the same problem can often be very interesting!

Good luck, everyone, and happy coding!

Let's solve Codeforces Round 1123 (Div. 2)!