Krzychuo's blog

I've solved all 800-1300 rated problems solvable with C++. AMA
By Krzychuo, history, 17 months ago, In English

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17 months ago, # |
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why

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    17 months ago, # ^ |
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    At first, I wanted to fill whole profile activity bar with dark green for the meme. It didn't really matter for me what problems I solve to achieve that, so I've been solving 800* problems obviously. Few months in it became a routine and fun way to pass the time.

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17 months ago, # |
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when

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17 months ago, # |
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Any problems where you struggled ?

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    17 months ago, # ^ |
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    Honestly, yes, there'd been about 2-3 constructive problems at which I had to think about 20 or more minutes. I think there even was one that I had to read editorial for. Sadly I remember none of them.

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17 months ago, # |
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why waste time on easy problems?

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    17 months ago, # ^ |
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    First of all, I've noticed that my performance at solving Div2 A-C have increased drastically over past year. Another thing is that my ultimate goal is to clear up whole codeforces's problemset which is quite unrealistic, but it's worth a try. Other reasons had been explained above.

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      17 months ago, # ^ |
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      I think I'll try a strategy similar to yours to help increase my speed on div2 A-C. I don't think I'll try to finish everything though. Hopefully it works.

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17 months ago, # |
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how much time you spend on a problem before looking at the editorial?

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    17 months ago, # ^ |
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    Depends on the problem, but most of the time I try to solve the problem without editorial until I'm annoyed with the problem or/and I'm not progressing at finding any observations for a long time. Also if I find my approach unnecessary complicated after solving the problem, I read the editorial to check whether there exists some simpler approach.

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17 months ago, # |
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What about 800-1300 problems not solvable with C++?

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17 months ago, # |
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  • Can you Guide me with the problem I face while giving the contest? I can solve DIV2C most of the time while practising outside of the contest; however, solving some might take time. Still, in the actual contest, I could not build the intuition of DIV2C very fast, resulting in being unable to solve the problem(Most of the time). So what should I do to overcome this problem?
  • According to you, what is essential in a contest to reach an expert, fast solving DIV2C or solving DIV2D but very slowly?
  • Can you Review my profile and guide me to reach an expert?
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    17 months ago, # ^ |
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    I may not be the best person to ask for these things, but since this is AMA... In terms of profile review, I think you're doing good job upsolving contests you're taking part in (at least for recent contests). IMO you should focus on learning DSA on level not higher than segment tree (eg. binary lifting, difference array) and also look out for observations commonly reappearing in problems. (eg. $$$GCD(x, x+1) = 1$$$ or harmonic sequence sum upperbound)

    According to you, what is essential in a contest to reach an expert, fast solving DIV2C or solving DIV2D but very slowly?

    Depends on contest's rules, but IMO most often solving 4 tasks slowly will be better in terms of ranking rather than fast solving 3

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17 months ago, # |
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what happened on fifteenth of february?

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    17 months ago, # ^ |
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    I don't really know what you're asking about, I'm assuming you're asking me about the blank spot you're seeing at activity bar. It is caused by differing timezones, so according to your timezone, I haven't solved any problem that day.

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17 months ago, # |
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Why are some problems not solvable with C++?

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17 months ago, # |
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Do you feel it helped you solidify previous concepts and it'll help you solve harder problems like 1400+?

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    17 months ago, # ^ |
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    Not really, because there aren't too many concepts that you can base easy problems on. I wouldn't recommend solving these problems for practice to anyone, unless you're a newbie or you really want to practice fast-solving easy problems.

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      17 months ago, # ^ |
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      Do you recommend us greys to solve as many 1100, 1200, 1300 to go green?

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        17 months ago, # ^ |
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        I wouldn't go for quantity but rather quality. Whenever you solve a problem, try to fully concepts that appeared in it. Also from my experience, to get to pupil you don't even have to know any DSA except STL and maybe binary search, so try focusing on that. Very basic graph theory might come in handy too sometimes. Example problem

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17 months ago, # |
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I've solved all 800-1300 rated problems solvable with C++

Spoiler
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17 months ago, # |
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Hey I struggle sometimes in 1300 can you please tell what the most focused and basic thing you notice that every 1300 problem must not solved like any theorem or what : (

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17 months ago, # |
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I will ask again: why?

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    17 months ago, # ^ |
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    I don't know if I can come up with any more reasons, I just think it is fun way (for me) to pass time. I think the best comparison to this may be solving sudokus. Most commonly people will solve sudokus not for the real challenge, but rather to pass the time, because it's fun to solve them.

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      17 months ago, # ^ |
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      do you have more fun when solving 10 1200's in a hour or spending 2-3 hours on a 2400 problem

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        17 months ago, # ^ |
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        Depends on the problem quality, while grinding 800-1300* I sometimes (but rather rarely) had "Wow, idea used in this problem is really cool and original" moments. Example problem It also depends on my mood, but if I had to choose, then I'd select 2400 problem.

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17 months ago, # |
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Struggle a lot with DP problems any help you got?

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    17 months ago, # ^ |
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    Depends on your problem, do you struggle with modelling dp solutions, implementation, or finding optimizations to your dp's?

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      17 months ago, # ^ |
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      implementation and modelling.

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        17 months ago, # ^ |
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        In terms of implementation, I'd focus on learning top-down approach, IMO recursive dp's are much more intuitive than iterative ones. (as long as you know how to use recursion) I don't know how to help you with modelling part though. Best I can do is recommend solving whole CSES dp section as it contains some very classical dp tasks which you may benefit from.

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17 months ago, # |
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How can I see the graph/bar chart of solved problems according to their rating ?

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17 months ago, # |
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How long do you expect to solve every problem < 2100?

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    17 months ago, # ^ |
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    If I manage to ever do that, I think it'll take atleast 2 years from now.

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17 months ago, # |
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Can you please review my profile?

:)Glad to see your suggestions so that I can improve.

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    17 months ago, # ^ |
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    I'll just give some general ideas on how to improve, because it is hard to find your weak spots just by looking at your profile.

    • Always upsolve, it is best occasion to learn new things.
    • Read editorials after solving tasks. Author's solution may use better approach for the problem.
    • Learn STL, C++ is your tool, not an enemy. Mastering it will save you huge amount of time.
    • Solve problems from CSES problem set. It has a lot of classical problems you surely will benefit from.
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      17 months ago, # ^ |
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      Thanks a lot for your suggestion.

      I have one doubt, after the contest I upsolve most of the time but after 2 or 3 weeks of that contest if I again try those upsolved problems then I got stuck in it.

      Is this thing normal or not?

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        17 months ago, # ^ |
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        Well, it is normal to forget things. Whenever you encounter hard problem I'd recommend trying to explain solution in simple terms to someone (or yourself if you have no one to talk to). "If you can’t explain it to a six-year-old, then you don’t understand it yourself", but of course take this quote with a grain of salt.

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17 months ago, # |
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Congrats :)

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    17 months ago, # ^ |
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    Thanks, but honestly I wouldn't call that an achievement.

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      17 months ago, # ^ |
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      but still, you spent a lot of time on this, good luck with solving rest of the problems

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17 months ago, # |
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.

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    17 months ago, # ^ |
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    It's pretty hard (if not impossible) to point out some particular things that helped me achieved it. I'd say majority of CP-algo is what contributed the most to me.

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17 months ago, # |
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Did you takes notes when you learn some new topics

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    17 months ago, # ^ |
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    I'm never making notes on anything (unless i'm making calculations), so no. Whenever I learn new CP concept/algorithm I write it's implementation or solve problem related to it.

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17 months ago, # |
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Any advice on constructive problems?

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17 months ago, # |
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Congratulations! I enjoy doing the same. I have solved all (but few) 800-1600 problems solvable in Java. I am going through 1700s now. I am keeping few easy ones unsolved for a vacation where I don't want to spend too much time on Codeforces, but still like to solve 3+ problems a day ;-).

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17 months ago, # |
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Are you happy in life?

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17 months ago, # |
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Hi,Bro. I am also trying to make at least a year or 500 days stack in activity bar. But I did't make it all dark green. I am a beginner so I mostly solved 800-1000 rated problem. Nowadays, I am trying to solve 1100-1400 rated problem. I solved most of the problems in C but for now I am using C and C++ both. Wish me Luck : )

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