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Hi can anyone help me to find a counter testcase where my code gives runtime error. Got runtime error on test 3 and couldn't find the fix till now. Link:- https://codeforces.com/contest/1841/submission/209481108

Is G based on matrix expo on 2D dp?I figured out the dp but had no clue how to convert a 2D dp to matrix expo...

I have another solution to C different from editorial which is much simpler.The answer is that cell which contains a '.' and has greater than 1 adjacent '#'s.

Morning waking time:-7:30 a.m. Sleeping time at night:- 2:30-3:00a.m. (1 hour sleep in the afternoon)

See my solution using only binary search(as a fancy thing).

Thanks mate.

Hi can you share the intended approach for this problem(problem F).I saw in japanese editorial like some super vertex kind of stuff but it's hard to properly understand from it even with google translate.

One case is that when the maximum element which is n is not on the index 0.In that case you can bring n to index 0.The other case is that when n is on the index 0.Then whatever operation you perform n can't remain on index 0.So then we will bring n-1.Instead of doing casework for the 2 cases separately,we check both and take the best answer.Hope it helps.

First let's say maximum element={n if a[0]=n else n-1} Let indexMaxi=index of maximum element. fix r once as indexMaxi and once as indexMaxi-1. iterate over all l and choose the best answer. O(n^2) simple ,for O(n) you have to consider cases (I was getting frustated figuring out each edge case)... Solution

See it this way:- D and E are of same points.

Is G2 based on the fact like finding all unique GPs of common ratio upto 30 then doing some trick(no idea) to find GPs of ratio greater than 30 also using the GPs of common ratio upto 30?

Congrats bro.

Problem G is a nice implementation problem

You should have asked Um_nik directly.Why shitpost!

Thanks a lot :)

How to solve Make It Zero?are there any edit__orials for the round?

My O(nlog^2(n)) solution to problem E using small to large merging technique. Implementation

Thanks bro,the error was in the part where I was making sqrt(ac) using b_search function and then multiplying by 2.Instead I should have done sqrt(4*a*c) because the former one resulted in loss of some decimal values which could have been important.

I got FST in problem C. Here is the submission. Used my own b_search to calculate sqrt instead of builtin functions. Still FSTed lol.Any idea?

I think E can be solved using the small to large merging technique.

Yes problem D looked like a cool dp problem...

Team: 'Blitzkrieg Boys' from NIT Kurukshetra

Members: MasterRayuga,deepak_changoi,Dontony

Regionals: Qualified for Kanpur — Mathura, Location : Mathura

Preferences in problemset: Balanced contest.

Can you share some resouces for learning flows?I want to upsolve this problem.

My clean O(n*k) dp approach for problem D not involving any casework for positive and negative x. Link

O(n) solution for problem C. https://codeforces.com/contest/1794/submission/196020227

How many people will be selected for onsite round?

Excited...

This is dangerous bro...I hope codeforces finds out a way to remove this possibility.

This will be my last year participating in this contest probably really hoping that it happens.

Missed the last condition in G

I think that was a joke...

This much hard university interview...

Subscribed.

Go to edu section of Codeforces.It has really good explanation and problems on binary search

Is square root decomposition the intended solution for problem F?

Was D related to some kind of dp?

The problems were really great.We loved to solve them.But why there is no option for upsolving?

Can you share your code please?

Did you got ac with that? I got WA with this approach.

Yupp,I also got it now. But this would be pretty much implementation heavy right? Storing how many subarrays ,prefix, suffix, sum modulo 3 for that range for each 0,1 and 2

I also had similar issue with problem B.I converted the recursive soln to non recursive using two stacks(postorder traversal) but sadly after 14 mins contest ending.

Thanks,got it now.

Maybe you have to do the same thing after 2 hrs in this contest(considering the difficulty of global round).

Thanks. Totally understood.

From the editorial can anyone explain that in the ith timestamp why every unvisited node (upto i-1 th timestamp) is visited atmost once? Let's assume that the operation is t=1 and "no" is an unvisited node upto i-1 th timestamp.Then "no" can get visited from no-x,no-2*x,no-3*x.... (assuming all of them have been visited upto i-1th step). I am telling this according to the solution given in the editorial. Can anyone please tell me where I am wrong?

Thanks.

Thanks.

Can C be solved using iterative dp?

Same happened with me in sublime .It was not able to produce output on the testcase 500 250. I checked in custom invocation of cf and there it ran perfectly.

Try to reduce the for loop inside the recursive function to one or two recursive calls.

Can anyone tell how to solve C using iterative dp?

The mistake was different. I was computing the lca wrongly.But anyways I will keep your adivice in mind.Thanks.

Thanks bro a lot. I got rid of the MLE thing.

Solution for C using seg tree:- https://codeforces.com/contest/5/submission/110141648

Thanks, uninstalling the antivirus worked.

Thanks.

I think it's broken again.

Yes, I too get stuck in critical observation type problems. Any help on how to improve on problems like that(B of today's contest for example) is appreciated.

Thanks for the reply.

You shouldn't make fun of someone who is trying to improve.

You know most probably I think.

Its not working bro.

Yes you are right. Actually facing this thing from the last Div 3 round.

Okk.Thanks for the reply.

Right now I am solving 1500-1800 rated problems in Codeforces. I think it helps a lot. Previously I solved problems from Leetcode, but to become better at Codeforces, according to me, solving problems from Codeforces is better.

I am also now doing the same practice. Thanks for the reply.

Try to solve standard problems on dp. If not able to solve, understand it properly and solve some similar problems. Solve 50+ problems(if totally uncomfortable) and you will be good to go.

Can anyone help me where my code fails for B. Link:- https://atcoder.jp/contests/arc108/tasks/arc108_b

There is no option to delete the comment.Srry.

Okk.

I tried E with some precomputation.My time complexity is O(N^2). 5 pass.But it failed the test case 11.

I am interested(if you consider a specialist). Note:-Please consider.

Can anyone tell what is wrong in this code. for B. Link:- https://codeforces.com/contest/1406/submission/92640232

Thanks a lot brother.

Bro it can be checked.I couldn't solve it during the contest,but after the contest I upsolved it.

First sort the and then continue extracting elements from the back.

Yah I got it bro.Thanks for the test case.It also fails for the this test case also:- 3 2 3 10 128 130 137.

By now,I know that one among c[i..n] is maxi.So I checked that for a particular i, for which value of a[i]&b[j],the OR with maxi comes out to be minimum.That's it.

I have a better approach for Div 2 C.For each a[i],find the minimum value of c[i].Then find the maximum among all the c[i].Now brute force this maxi with all possible a[i]*b[j] to get the ans. Time complexity(O(n*m)). Link to my submission:- https://codeforces.com/contest/1395/submission/89722222. Think a little bit and you will get why it works.

Ok bro,no problem.Thanks for your efforts btw.With your permission should I explain my approach?

Can you please check my latest submission on my account.Please!

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You can use CF predictor to reduce your mental harrassment

Bro try passing the string by reference.I also had the same problem.It worked for me.

Bro I actually got it,by passing the string by reference.

Bro can you please tell me why my this solution got TLE. Link:- https://codeforces.com/contest/1385/submission/87166057

I also have the same doubt bro,though I am not able to get accepted till now.

Very good step.

Not excited

It worked by declaring the array as global.Thanks!

Thanks a lot!

Thanks a lot Sir.It worked. Can you please why it was getting TLE- https://codeforces.com/contest/1336/submission/77683830 and now got accepted- https://codeforces.com/contest/1336/submission/77685443

Auto comment: topic has been updated by Dontony (previous revision, new revision, compare).

You are right

Thanks a lot.It would be really nice of you if you help newcomers like me.

Ok Sir.No problem.By the way,I came to know that you are from Calcutta.I am also from West Bengal.Can you please give me some suggestions on how to improve my rating?

I am willing to practice with you daily.But my rating point is 1360 as I have started CP only 3 months ago(1st year of college).Will you please consider me?