# Hello Codeforces!

#### Solving 5 problems in Educational Codeforces Round 164 (Rated for Div. 2) gave me an unexpected +125 and I leaped across *1800 right into the lower bounds of purple. This means I am finally touching the eligibility to take part in contests with many of the brightest competitive programmers!

Within the 3 months after registering my account, I have learned many new techniques, with the most representative being modular inverse, **segment tree with lazy propagation**, fenwick tree and Tarjan's algorithm. I really believe segment tree is something like "Welcome to the realms of div.1!" However, my rating revolved around 1790 and was incredibly stable and I doubted if I was improving. But in several training sessions and VPs I managed to do well. Never mind, CM has come, and I finally start to believe I can go on in CP and reach for my goal in an ICPC regional. The next step is to defend CM, and I'm planning to learn:

- More STL
- KMP and AC automaton
- Decomposition and Mo's algorithm
- Maxflow and Mincut: Dinic's algorithm
- Euler's sieve
- Matching on a bipartite?
- Suffix array of a string?
- Fast Fourier Transformation?
- Heuristic searching and pruning techniques?
- More ad-hoc constructive problems
- More ad-hoc dp problems

Fun fact: Div 1+2s finish at 1:35AM in China, so I did not register for CodeTON 8 because I would get up early to enjoy cherry blossoms the next day, but when upsolving I solved ABC1C2, skipped D and took down E within 90 minutes and the trip cost me 2 TON...

Great Work man. Any suggestions for newbie please?

Focus on Greedy and Math Problems, Wish you the best!

your graph shows really nice progress how did u train ? also how did u handle editorials

chinese do not train, chinese just EXIST

if i had realized he was chinese i would'nt have asked

What does "handle editorials" mean? Basically I upsolve problems up to Blue difficulty label(CSP-S+ ~ Provincial selection-) on Luogu. If I stare at the statement for 20mins and have no idea I simply go to the editorial.

Well, what i wonder is how does both of you progress so fast? You are both amazing though.

i guess the same thing i just choose problems way too hard read their editorials and never learn aglos or data structures

my congratulations!

Congratulations!

You must have a very strong mathematical background. It is not possible to reach CM so soon without already being a pro at maths.

Actually I major in Computer science, and some of the required courses include:

I've tried CP in 8th grade as well, and some of the easier techniques are remains from that.

Congratulations!

Purple is 1900-2199

https://codeforces.com/blog/entry/20638

No, purple is 1900-2099.

what resources you depend on while learning a new topic ?

How did you practice? how did you choose your problems? was it randomly? also what advice you would give me so i can reach cyan in the next 2 months

I believe the choice of some of these algorithms is a bit hasty. I don't think I ever used an FFT, suffix array, Dinic algorithm, Mo algorithm in a Codeforces round, and I left the domain of CM many years ago. Structured understanding of what's out there in C++ STL and what is not is more important, I guess. Dp techniques (again, not very advanced) are also of use.

Thank you for your suggestion. In fact, experienced contestants agree that FFT and suffix array are a bit too advanced for me now, but in the technique-dense Chinese NOI/NOIP, knowing Network Flow and Mo's do make sense. At least for the first 3 topics, their template problems are labeled BLUE difficulty on Luogu.

Maxflow: P3376 <TEMPLATE> Maxflow

AC automaton: P3808 AC automaton (Easy version)

Mo's: P2709 Little B's queries

Since many problemsetters of XCPC in China have a strong NOI background I believe learning these are of use. But I do agree how to model a problem into a template is the more important part.

Also: GL World Finals!

Well, I'm only discussing Codeforces specifics. If you're preparing for the Chinese olympiads as well, the priorities should be a bit different.

Congrats! And I solved 5 problems in that round too and gained +135 rating. It feels great!

how do you pick problems to practice ? do you practice on other judges too?

Congratss! Any suggestions for Constructive Problems? I have been doing CP for 4 years now (although not regular) but I still have no clue how to tackle them.