Hi Codeforces!

For those who don't know me, I competed at ICPC World Finals (2013 and 2015) and was a World Finals judge in 2018 and 2019. I've recently begun competitive programming again, and my hope is to regain international master or eventually grandmaster status.

One thing that helps me improve is writing "slow" analyses of problems I solve. Instead of just explaining the final solution, I try to reconstruct how I got there.. what I notice, what I try, where I mess up, and which insights eventually led to the solution. I did this when I trained for World Finals 2015, and it helped me improve quickly (peak rating 2396) and other people found them useful.

So I'm reviving them now, both to help my thinking as I hope to become good at cp again! And to help others who find most editorials a little too "fast".

I will mostly focus on Div. 1 A — D problems (which is where my skills are today, and most helpful for someone going from candidate master to international master) starting with:

• 2239A - Nim Game Is XOR Game — Analysis
• 2239B - Decidophobia — Analysis
• 2239C - Revival — Analysis
• 2239D - Hunting the Beast — Analysis

but I will have many more coming, and please feel free to message me in codeforces if you have a request for a specific problem.

Hello everyone. Here is my "analysis" on today's 550 problem from TopCoder SRM 648 (Div. 1).

(Link to Blog Post)

This was a pretty hard problem for me. I was unable to solve it :(. After the contest, I tried to understand the Accepted solutions. After this, I wrote this analysis to (hopefully) "recreate" and recapture the ideas necessary to solve the problem on my own.

I hope this helps!

Hello,

Here is one of my in-depth problem analyses for the recent SRM636 500 problem (ClosestRabbit).

(Link to Blog Post)

As usual, please comment below if you have any suggestions / questions.

PS: The blog is going through some "renovations". I decided to move it away from the infamous WordPress. So some features/old-posts may be missing right now.

Cheers!

If anyone was wondering, here is my personal post about the 550 problem from yesterday's TopCoder round.

Link to Blog Post

In summary, this problem required modular arithmetic and a trick I've seen used to solve the Coin Change Problem. Let me know if you have any comments or questions!

Here is a short editorial on TopCoder SRM 605 Medium problem, AlienAndSetDiv1. As mentioned, I would like to share more as I am learning. Maybe this will help me learn better and help others learn as well! Spoiler

I call it "Theory of Problem Solving": a blog of tutorials and in-depth analyses of the problems that I solve. I would like to share this with everyone in the Codeforces community!

It's just getting started, and many of my analyses are really long, because I wanted to focus on the process more than the solution. Anyway, take a look at the analysis of Codeforces Round #224 (Div. 2) E — Ksenia and Combinatorics!

Feel free to make comments or requests for specific problems!

Thanks everyone! Happy Coding! I will be posting more soon. Cheers!

Link: http://dojiboy9.atspace.cc/contest/