[Long Post Ahead]

This is my first post on this subrddit. There have been a few high efforts posts related to this on this subreddit before, the two I found are this and this. I believe I should be able to make some improvements, and add a few extra resources, hence I am making this post.

Background: I did CP purely as a hobby, with no intention of using it for placements (I am studying EE). I did CP actively just during my first year, and have reached Candidate Master (1900+) @ Codeforces. I am also in active contact with many high rated CPers, and have a sound idea of what resources are good.

I did CP almost exclusively in C++, since it has some "community advantages", as I would like to call it. Most submisssions will always be in C++, and model solutions will also be always made in C++, if not in other languages. You are also more likely to get help since there will be more users who would have used C++. Also, you will find more pre-written libraries/ implementations in C++. You can certainly do it in Python or any other language you like, but it would be non-meta. I did not use any course as such to learn C++, but rather learnt by reading up documentation on cpluslus and actually writing code. Even for Python, I used pythonds3.

BOOKS

• Kostka, Bartosz. "Sports programming in practice." Master’s thesis, University of Wrocław, 2021. Link to book. This is a book on competitive programming by kostka, an Ukrainian International Grandmaster.

• Competitive Programming 4.This is a much more comprehensive book, and is sold in 2 parts. The books can be bought from here. However, you can find both books available online as well, but I am not including the links here (they are easy to find).

• Introduction to Algorithms (CLRS). It would be unfair to not include this book. The book is very easily available online (I had got it from here). There are also several courses based on this book, that you may use to complement your understanding like MIT's Introduction To Algorithms (SMA 5503). There are also several online resources with solutions to CLRS excercises, such as this.

COURSES / PLAYLISTS

I never personally used any of the DSA/ CP playlists that are popular here in India, but that does not mean I haven't watched any such content. Some Youtube channels, playlists or courses. The ones I found valuable are listed below -

• Codeforces Edu Section - The ITMO Academy: Pilot Course has content on Suffix Arrays, Segment Trees, DSU and Two Pointers. It also comes with practice section with some questions. It is taught by Pavel Mavrin (aka Pashka), who is by far my favorite teacher I have learnt algorithms from.

• A&DS English Course is an incredible playlist, once again taught by Pavel Mavrin. However, most of it is pretty advanced and has stuff you are likely to never need in actual contests. However, I really enjoyed learning from him (specially DSU, Dynamic Progamming and Graph Games).

• USACO Guide is probably the most exhaustive resource ever compiled. It has various sections that are meant to be navigated in given order. It has both explanations for the topics and practice problems.

• YouTube Channels of various well known Competitive programmers also have several videos, which may come in clutch for various topics. Such channels include those by Errichto and Colin Galen. Colin in particular has some topicwise practice streams that really helped me out. Umnik's channel has screencasts of him solving several contests (Codeforces, Atcoder .etc). There are several other such channels, and it will be impossible trying to list them all.

BLOGS / ARTICLES

• Codeforces in itself is an invaluable collection of resources. There is an uncountable number of useful blogs that cover almost anything you will ever need. From editorials, to detailed tutorials on various algorithms and/or techniques, there is a lot of stuff that you just need to discover. The Codeforces Catalog may be useful in this treasure hunt. There are also serveral blogs that just aim to be a compilation of useful blogs, like this and this.

• Algorithms for Competitive Programming, commonly known as "CP Algorithms", is a very good collection of well written articles on various Data Structures and Algorithms, and each article comes with a link to some practice problems to implement what you learnt.

PROBLEMSETS / PRACTICE

• We all know that Codeforces and Atcoder are two of the most popular CP platforms. However, actually navigating the problemsets to find a problem of a suitable rating might me a little irksome. CFTracker allows you to filter Codeforces contests (based on Division), view which questions you have solved and so on. Kenkoo is the website that does the same job for Atcoder contests. I am not aware of any such tools for Codechef however.

• The CSES Problemset is a very famous and well regarded problemset that has is supposed to be a collection of "standard problems". It has a section-based approach. You will find several editorials to its problems on various blogs (even on Codeforces). For the Dynamic Programming Section, you can refer to an editorial in 2 parts - first part by Grandmaster icecuber and the second part by me.

• The Atcoder Educational DP Contest is a very good collection of standard dynamic programming tasks as well.

• This is an example of a Codeforces group that has some private contests (gyms) for beginners that may help you in early practice. Here is another.

PROBLEMSETTING

Maybe you are finding it more fun to create new tasks than to solve existing ones? Well, then you would need to try your hand at problemsetting. I have a working idea of how to create tasks, and also what goes on behind the scenes of making a contest (atleast on Codechef). This blog by darkkcyan is an extremely helpful step-by-step guide on how to use Polygon to create tasks.

That will be it from my side. I don't think I am missing something, but if I do recall anything (highly unlikely since I have long retired from this hobby), I will make sure to add it. Feel free to suggest any changes / corrections.