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GustavoLopesOliveira's blog

How Can I Solve Problems Harder Than 800 Rating?
By GustavoLopesOliveira, history, 21 month(s) ago, In English

Hello, I am Gustavo from Brazil.

I would like some tips to help me improve. Currently, I can solve problems rated around 800 in Div. 4. I can solve problems A, B, and C in Div. 4 contests, but no more than that. In Div. 3, I can sometimes solve problem A, but I don’t know what to study to improve.

I’m in my first year of Computer Science and about to start my second semester. So far, I’ve only had one introductory algorithms course at university. I’ve learned about stacks, queues, sets, multisets, vectors, pairs, and algorithms like sort, upper_bound, and lower_bound. At the beginning of this year, I’ll also learn about trees.

I’ve attached an image of my solved problems. Most of them are rated 800, and I’ve solved 86 of them so far.

What should I do to get better? Any advice is welcome!

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21 month(s) ago, hide # |
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I strongly suggest you use CP4 books and kattis to start your journey, rather than codeforces. The books not only teach you relevant topics for competitive programming it also has sections with questions. Each section has 2/3 starred questions (which is like most relevant questions for that topic). I have done all starred questions from chapter 1 to 7 (and like half in chapter 8 when I got tired of doing the book and migrated to codeforces. Mind you the book has 9 chapters). I think the book is a great source to learn the fundamentals. Also, codeforces questions are usually more creative, so I think it is hard to progress by just doing them, as at times you won't know whether you lack skill or just need some observations to solve a problem. This is what have worked for me.

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    21 month(s) ago, hide # ^ |
     
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    Btw I am not sponsored by them

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    21 month(s) ago, hide # ^ |
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    These books?

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      21 month(s) ago, hide # ^ |
       
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      Math helps a lot in competitive programming; that said the topic that helps the most is number theory, which is the kind of math you see most on math competitions (such as OBM)and discrete math courses on university. To pass university I had to study a lot of hard questions in trigonometry, complex numbers, combinatorics, linear algebra (I fucking saw singular value decomposition in high school to solve some physics problems with harmonic oscillations, can you believe it??), but from all those topics I only use combinatorics in CP. so you should be fine by just learning your math curriculum + some extra number theory and solve some math competition problems.

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21 month(s) ago, hide # |
 
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I would suggest trying to do harder problem for 30~60 minutes (even harder question may require longer time),

if you really can't do it, then read the editorial (or tutorial/answer).

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  1. Go to cses problem set.
  2. Try to solve.
  3. If can't learn the topic first form CPH book or somewhere else.
  4. Solve some easy problem on leetcode/hackerrank on that topic
  5. Go back to cses, try to solve, spend at least half and hour.
  6. if can't, read the editorial.
  7. try to solve
  8. if can't view the solution at a glance
  9. Now to try to solve again after seeing solution
  10. if can't break down the solution and practice few times
  11. Go to next question
  12. Repeat the cycle
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21 month(s) ago, hide # |
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I'd go on timus, and just start solving the problem set, I'm pretty sure that with the first 100 problems of timus you would improve way more than just doing another 100 problems rated 800.

I think in general you need to pick better problems. 80 800rated problems are way too many problems.

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21 month(s) ago, hide # |
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If your basics are not strong then learn some basic algo-DSA-STL then try again.

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