I really like good blog posts. And that's the main reason I like Codeforces. But as we all know, it's hard to find good blog posts here. So let's help each other and share our favorite posts, which were uploaded to Codeforces in the last year! I will share my top 10, and I encourage you to share some of your favorites in the comments.

#### 10. Heuristic algorithm for Hamiltonian path in directed graphs by slime

An absolutely incredible algorithm which kinda sometimes solves the Hamiltonian path problem on some random and special kind of graphs.

#### 9. I compiled a list of almost all useful blogs ever published on Codeforces by parveen1981

This blog has a purpose that's similar to the purpose of the blog you're reading right now. A great source of interesting blog posts!

#### 8. Fast modular multiplication by orz

Some really interesting algorithms that help multiply 64-bit numbers modulo without int128.

#### 7. Competitive Programming Hall of Fame — cphof.org by Ra16bit

A new awesome resource, that collects all the different achievements of CP-legends.

#### 6. The Ultimate Topic List and (The Ultimate) Code Library by YouKn0wWho

These are two different posts, but I would like to combine them. This is a really nice collection of materials and implementations of tons of different algorithms and data structures needed for competitive programming.

#### 5. My opinion on how to practice competitive programming by Radewoosh

Some really interesting thoughts from Radewoosh and a really long and engaging discussion in the comments.

#### 4. C++20 Is Released by MikeMirzayanov

The main treasure of this blog post is the comments! So many interesting tricks and tips for C++20.

#### 3. [Tutorial] GCC Optimization Pragmas by nor

I never used pragmas because I didn't understand what they're doing. Finally, there is a resource where I can close this gap in my education :)

#### 2. Lambda optimization certificate by never_giveup

A really interesting discussion about an algorithm which is around for 5 years but still isn't really understood by the public. I learned a lot from this blog post and after that started researching a lot of things about lambda optimization (a.k.a. Lagrange optimization a.k.a. aliens trick) on my own and figured out that I didn't really understand a thing about it before.

#### 1. [Tutorial] Li Chao Tree Extended by rama_pang

In my opinion, it is the best blog post and the best new data structure of the year. It's absolutely incredible and simple at the same time.

I hope you learned something new today. I'm looking forward to reading your favorite blogs. Merry Christmas and Happy New Year.

I suggest Things I don't know by Um_nik. It prevents people from learning useless algorithms, and helps us to understand binary search!

I'd just like to link to an amusing post by Elegia no one else understands: https://codeforces.com/blog/entry/92183

About the second article. No, I don't think the way of restoring the certificate in the post is general enough. Should I write another post? XD

Yes! Absolutely! I know one more way (combining two paths with the minimum and the maximum number of segments for fixed a lambda), but it works only if the weight function satisfies quadrangle inequality (which is almost always true but not always).

That was what I was trying to say :) but I didn't find a case where both ways do not work.

I once wrote a post in Korean detailing all the DP optimization trick that I was aware of. At that point, I wanted to translate this into English but was too lazy to finally do that.

Yeah, me neither. But I don't lose hope :)

Thank you for your link. It would be great if you'd translate it, but I think I will be able to read it with google translate.

Great post helped a lot

0, Top 10 best Codeforces blog posts of 2021 (in my humble opinion)

Great post