### I_love_Tanya_Romanova's blog

By I_love_Tanya_Romanova, 2 years ago, ,

Hello everyone!

I want to invite you to participate in February Clash at HackerEarth. Contest is scheduled on February, 20. Contest duration is 24 hours, so there should be some comfortable time for every timezone :)

There will be six tasks in a problemset. Five of them are standard algorithmic problems with partial solutions allowed — you get points for every test that your solution passed. And the last task is an approximate problem — your score for this task depends on how good your solution is comparing to current best solution.

shef_2318 is author of this problemset. If you want to get an idea what to expect — you may check his previous contests at HackerEarth, CodeChef and HackerRank. Even if you don't need it in order to participate in Clash — I would advice you to take a look at them someday, because there are quite a few really interesting problems there.

I was working on this contest as a tester. I believe it is going to be an interesting one, as usual :) I hope that several problems will be not too hard for beginners (don't give up and show your best with partial scoring — even very naive solution may give you some decent points; and 24 hours should be enough for you to read all problems and find some tasks which you can solve) while some tasks are challenging enough to make this contest interesting for more experienced contestants. Even if you think that classic part of problemset is easy — go on, try to beat other contestants on approximate problem :) shef_2318 also worked on this contest as translator — you will be provided with problem statements in English and Russian. Also I want to thank belowthebelt for providing technical help and doing his best on fixing all issues and improving HackerEarth platform.

As usual, here is one more reason for you to participate in this contest:

1. $100 Amazon gift card + HackerEarth T-shirt 2.$80 Amazon gift card + HackerEarth T-shirt
3. \$50 Amazon gift card + HackerEarth T-shirt
4. HackerEarth T-shirt
5. HackerEarth T-shirt

Good luck to everybody — I hope to see you at the scoreboard :)

Upd. Contest has ended, congratulations to winners:

1) eatmore

2) mugurelionut

3) Carsten Eilks

4) RomaWhite

5) Egor

All editorials have been published.

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 » 2 years ago, # |   +10 The contest has started. Good luck, everyone. 23 more hours to go. :)
 » 2 years ago, # | ← Rev. 2 →   +29 The judging system, at least on the challenge problem, is broken. I've submitted dozens of times and only two of those submits have been evaluated.UPD: Downvotes won't fix it.
•  » » 2 years ago, # ^ |   +15 Bump; the problem persists and I'm not the only one affected by it (as it seems from the other comments).
•  » » » 2 years ago, # ^ |   +46
•  » » 2 years ago, # ^ | ← Rev. 2 →   0 Apologies, We will look into it. The problem Rings (approximate problem) had some issues. We will fix it.Regards, Sreeram
 » 2 years ago, # |   +16 Just another bugreport: sometimes C++ submissions are compiled using old g++, causing compliation errors.
•  » » 2 years ago, # ^ |   0 Hey Aleksandr,We need few details about the issue you are facing. Which version of g++ did you use to compile your program locally? Can u PM me your username? We will resolve the issues and update the scores.
•  » » » 2 years ago, # ^ |   0 You may check my submissions too (I've send the same code several times and sometimes was getting CE) See for example submission id 3438775. It's in c++98 mode for some reason
•  » » » 2 years ago, # ^ |   0 I was also getting random Memory limit exceedings, See for example 3436852 — resubmission got OK
 » 2 years ago, # |   0 How to solve this problem in February Clash : https://www.hackerearth.com/february-clash-16/algorithm/sequences-everywhere/ Can anyone help me out with this problem ? This is my solution : https://www.hackerearth.com/february-clash-16/algorithm/sequences-everywhere/submission/3440968/
•  » » 2 years ago, # ^ |   0 Editorial for this problem has been published already, plus you may check solutions by other contestants. Brief idea of solution — you can count how many sequences will have second element equal to X — and value of X isn't going to be large, so you can try all of them.In your solution you made an assumption that length of sequence solely depends on remainder modulo 12. It is close to being correct, and it actually makes a lot of sense — if number isn't divisible by 12, it is not divisible by either 2, 3 or 4 (and you can figure out on which of them by considering remainder modulo 12). However, consider sequences for number 60: 7 2, and for number 420: 8 3 2. Both 60 and 420 are divisible by 12, but only one of them is divisible by 7, and that leads to having sequences with different lenghts (while remainder modulo 12 is same for both numbers).
•  » » » 2 years ago, # ^ |   0 Thanks a lot for giving me a test case where my solution is going wrong... The contest questions are really good :D
 » 2 years ago, # |   0 Contest has ended! Thanks for everyone for participation. It was sad to see that something goes wrong with judge; I hope it will be fixed till the next contest. Still a lot of skilled contestants showed their best :) It was interesting to watch how leader changed several times, and how standings in top5 were changing even in last 30 minutes of contest.All solutions by contestants should be available already; for 4 problems solutions by tester and editorials are going to be added in next few minutes. For Light it up they'll be added a bit later, today in the evening.Feel free to share your thoughts about problemset and contest in general and to suggest any improvements.
 » 2 years ago, # |   +8 I don't see setters' solutions below editorials. "Light it up" was an amazing problem. One of the most interesting ones I solved recently. "Game of divisors" was very strange. I wrote the recursive solution with memoization and then saw the "pattern". I wasn't satisfied after getting AC but whatever. Though the proof in the editorial is nice and simple. After seeing the editorial I would call this problem "I'm not even mad, that's amazing". "Sequences everywhere" — good medium problem. "Just shortest distance" — very good easy problem. "Square" couldn't be new and original. I've never implemented it but I encountered and thought about it. Did anybody use the randomized linear algorithm described here or here? Does it work for this problem? What about collinear points?
•  » » 2 years ago, # ^ | ← Rev. 5 →   +13 My solution for "Square" from scipy.optimize import minimize def f(a): # Returns answer if square is rotated on alpha # Everything is standard start = 0 while (start <= pi): try: ans = minimize(f, [start], bounds=[(0, pi)]) res = min(res, f(ans.x[0])) except: #wierdo, ignore pass start += 0.08 print res 
•  » » » 2 years ago, # ^ |   0 I had something like this, except I found the convex hull and if it was small enough, I tried much, much smaller steps in the angle (around 10 - 7). And used C++, of course :D
•  » » » 2 years ago, # ^ |   0 Did this solution pass? I tried a similar solution but could not get more than 66 points.
•  » » » » 2 years ago, # ^ |   0 Yep, it did
•  » » » » » 2 years ago, # ^ |   +2 That's interesting- I have an almost identical solution but still can't pass all the cases. I'll be grateful if you can help me figure out what's happening. Code