Hello everyone, I was trying to solve CSES — Sum of Divisors and finally found a solution within a complexity of O(sqrt(N)), and it worked. However, the problem intrigued my interested so I searched about it on Google, and came across this article explaining a solution to the same problem but with a complexity of O(log2(n))! the observations mentioned in the article are exactly the same I used to build-up my solution, but I don't understand how they consider it as O(log2(n)) or if they are doing something different with the code that I don't get.

[SPOILER]
In regards of the problem, the main observation is that there are segments of numbers that within each segment, theses numbers will have the same number of occurrences in the total answer. In addition, the number of theses segments is equal to the number of factors of N. In conclusion, the problem is about finding the factorization of the number N (as I guess)

So, what is the most efficient way to find the factorization of a number N? what is the most efficient way to solve the problem? is there anything I am missing with the blog mentioned above?

Thanks in advance!

Hello everyone,
I participated in the last round, solved Div2[A-B] within 25 minutes, then moved to 1330C - Dreamoon Likes Coloring which I got stuck solving it until the end of the contest. I waited for the tutorial.. then I finally got this:



Is writing tutorials really about giving the final answer (formula or something), or it's about explaining how we can get to that answer? I'm not judging anyone here. I'm just asking Authors for the upcoming rounds, please don't just give us the final answer, we can find it out from other participants' codes. it's really nice and helpful for lots of people (at least we with low rating) to know the observations and tricks before reaching out to the final answer. Or idk, is it something intuitive and I'm such a noob?

Hi everyone
I've just wrote this code 72243144 that has the complexity of O(n.log(n)) which is the same run time of the tutorial solution but I'm stuck with TLE! any help about what's going on? thanks in advance

Offline training is important in the daily life of a competitive programmer, where you solve the problem and find the idea while you are at University, traffics, etc.. then code it when you are back online (especially in countries where power outages are such a usual daily habit)
And PDF problemset would be very helpful in that, so can there be some way to get Codeforces problemset as PDF. Or is there any OJ which offers that?

Hello everyone
about half an hour ago I participated in COCI contest, and I liked it very much, especially with the gradient difficulties in the problems, so is there any Online judge where I can submit my solutions for old COCI problems ?, or is there any way such that I can upload COCI contest in our Codeforces training group ?.
sorry if my English was bad and thanks in advance ..

Hello everyone
Here in Syria we have a lot of power outages (more than 16 hours everyday), you know, it's the WAR.
but luckily I managed to install ubunto and then CMS. I need your help if you can tell me about online judges that give you it's problems input and output files, like USACO, COCI and Atcoder recently.
thank you very much and sorry for my annoying questions in my last three blogs.

Hello everyone
In my practice (out of contest) I can solve Upto Div2_D problems, but when I face problems that I need math, numbertheory or counting methods skills to solve it, suddenly I stop and can't solve it without reading tutorial or I can't solve it even after reading the tutorial!
I'm asking if you can help me by giving me books, websites or anything that can help me in my dilemma.
Thank you in advance =D

Last 2 rounds were mirrors (they didn't pay the problem setters). Div.1 rounds have become much less frequent, and so have become Div.2 rounds. I have a friend who had had his round on queue for over 1 year (which means they have a very large number of queued rounds), and still there are no upcoming Codeforces rounds on contests page! Why is that Codeforces? .

Hello ..
this is what I'm telling my code to output :3 :

AND this is the output !!!

like you see , there is equality between temp and check but the output is different !!
full code : http://pastebin.com/8v0GgHXd
Thank you in advance :D

Hello Everyone Recently I installed Ubunto then CMS to start my serious training for SOI then IOI then to ICPC :D
CMS has been installed successfully but the problem is that I want to train on-line with my friends , each one from his house
Can you help me by telling me how I can link my CMS with on-line domain or what I need to do that .
thanks at all :)

Hello everyone ... recently I learned C++ language and joined to competitive programming World , I Just want to know if OOP ( Object-Oriented programming ) is important for me !? , such as " Struct " && " Class " .. Thanks in advance =D