Hello Codeforces!

I'm here to announce the release of MathMash!

It's a Math contest platform pretty similar to Codeforces in contest structure. Each user is given an initial rating of `1000`

and it's updated after the end of a contest that the user participated in, based on his rank in the contest. It also has a community which I put a lot of effort into. The community is made up of mini communities: Any user can create his own forum, add admins and start a community himself.

I also tried to add some facebook flavor to the site. You can make friends or follow other users. Whenever any of your friends posts or comments anything or someone upvotes your post/comment you'll get notifications.

I posted about the basic functionalities of the site in this MathMash post.

So today I'm hosting the first contest of the site. The contest consists of 7 problems to be solved within 2 hours. It'll start on UTC 2:00PM today.

You're all invited to join the contest. Hopefully we will fun!

It's awesome.

Could you explain how the contest will work? The problems are project euler style? Or IMO style? I couldn't clearly find it from the blog post.

They are project euler style. You need to input the answers to the problem. Similar to this problem.

Any submission penalties?

At the moment, no. But I'm open to any new suggestions. Should we assign each practice problem some points? Or maybe solving a practice problem increases user reputation?

But I've set a limit of

`20`

submissions per problem in a contest, because otherwise anyone can get a problem right by submitting enough times. I'm not sure if setting a limit is the best way to deal with it. Again I'm open to your suggestions. Let me know if you have any other ideas.But contests do have time penalties. Problem no.

`x`

costs`2^x`

penalty for each minute passed. For example, suppose, problem`A`

contains`100`

points. Then if you solve it correctly`5`

minutes after the start of contest, you'll get`100 - 5 * 2^1 = 95`

points.How can I know if my answer to a problem is right?

It'll show you an "Accepted" message. Try solving this problem for example.

My Submit button doesn't work.

Google Chrome Version 64.0.3282.186 (Ubuntu)

UPD: Oh, my bad, didn't see where I need to type the answer.

The same happened with me. It should be highlighted somehow.

Are the problems supposed to be solved with or without the help of programs?

https://www.mathmash.org/problem.php?prob=2 doesn't require programming but the constraints allow for people to write programs to find the solution.

Practice problems are just for fun, so if you enjoy coding the problems you're welcome to submit the output of your code. But writing programs for contest problems are

notallowed, as it takes effect into your ratings.As contests doesn't require any programming skills, why not to post it on AoPS? :)

How can you prevent cheating?

Cool website, but needs some fixes.

As cool as

a^{2}+b^{2}=c^{2}theorem. :)Seriously? You don't know any cooler theorem? :\

Only Pythagoras is real shit. Tell me yours.

Pythahoras theorem, is, shit? How you dare?

Dude, U don't understand the pun.

a^n + b^n = c^n doesn't hold for n>2 :P

problems not working

Now there is a second postpone. Edit: and the third one comes

It seems that problem D has wrong statement. Sets actually can be empty.

Providing such contests on math is a good idea (which has good sides of projecteuler and mathfights and just projects the concept of a big live competition onto mathematics), thank you for realizing it. Now I have several questions:

Are you going to make it a big platform for a huge amount of people? I mean, you can do it just for fun and not care about server's performance, thus making all following questions not having any sense.

Are you going to prepare contests by yourself? If no, are you going to pay to problemsetters? I'm not sure how it should be organized since preparing a math problem requires much less effort than for a programming contest.

Will your platform support pm's and questions during the contest?

Also I can prepare a couple of contests for it for free, I want this platform to attract more people.

Yes my goal is to grow it into a big platform and The pm's and questions feature won't take much time to add.

But the thing is that I had to put some good effort for the last 5-6 months to bring it into the current state. And I cannot really grow it now into a big enough platform all by myself. I could really appreciate some collaboration from others.

And I can't really pay the problem setters for much long as I'm a student myself and even the server costs really hurt. Although it could be a short-term solution till we find some other way.

A lot of thanks for your kind offer to prepare some contests for the site. I would be really happy if you could do that.

And I don't really know what to do about coding the problems. The only option of judging math problem results appears to be taking inputs and most of such math problems are vulnerable to coding.

Another idea a person gave me is to just take the proofs/solutions during the contest and hire some graders to grade the solutions later, after the contest ends.

Checking the solutions by eyes like in mathematical olympiads seems very difficult if, for example, ~500 contestants take part. Even if there will be a judging committee, it'll be very hard to check all solutions according to the criteria and not to miss anything.

Coding, however, doesn't look like an issue to me. It's just a projecteuler format. Moreover, it's about combinatorics, but geometry, calculus and many other branches look safe.

I think the idea of your webpage is very nice and I hope it grows, I have some comments to make.

The first is that I also want to volunteer to make some problems( for free of course), I am not as smart as many people who could volunteer but I have a good base( you can check my IMO results) and I am working on it.

Also about the whole cheating by coding I recommend you look at the Online Math Open problems( website: http://internetolympiad.org/pages/11-omo ). The harder problems are very interesting and also designed by very smart people so that it is very hard to code them. It takes a lot more effort to make problems of this kind but I have already invented some.

Lastly, I believe you should definitely make an AoPS post about the website, you could get a lot of participants and even some volunteers.

Of course you can help us set the problems. Your IMO results are a lot impressive too.

Although you won't be able to participate in the contests that you set problems for. Kindly PM me if you're still interested.

How to solve D and E?

D: Let's say that 1 goes to set 1, 2 goes to set 2. After that we construct sets number by number, for each number we have only 2 possibilities (it must go to any set without previous number), therefore answer is 2^18 (note that we counted the case when one set is empty).

E: We can note that P looks like ax^3 + bx^2 + cx. Then we can find a couple of values of P and interpolate.

It's more convenient to look at P's roots in E

For D, give 1 and 2 to any two sets and then it's easy to prove that each number can go 2 sets, so answer is 2

^{18}if we count empty set, or minus 1 otherwise (there is a little mistake in statement).For E, write polynomial as

a_{n}*x^{n}+a_{n - 1}*x^{n - 1}+ ... +a_{1}*x+a_{0}and after some calculations you will getn= 3. Also it is easy to getP(0) = 0, soP(x) =ax^{3}+bx^{2}+cx. Write it in given equation and again after some calculation you will get .Thanks you all)

Problem F solved than problem B while it was much harder. It was on my math quiz at school and I knew answer by heart, it's 615. Is there any way to prevent coding for contest? I mean it is really easy to write 5 line and get answer immediately while solution of problem is not that easy.

Can we upsolve contest problems? And how regular will contests be arranged? I really hope it grows and becomes popular. And don't let it die as the BdMO forum did :p

Yes, I did so since I missed the round. But there is no such features as "virtual contest".

I did not get a confirmation mail, I checked the spam folder.

I have this problem too.

I manually verified the pending accounts. You can try to login now. If you are still facing problems, kindly comment here.

Doubt cleared.

The problems aren't supposed to be solved by coding. See this comment.

Oh I see. Thanks!

Excellent initiative ! I love it ! I always wanted a website like this !

Will editorials be published ?

The editorials have been published here.

[user:DrSwad]I did not get a confirmation mail, I checked the spam folder.

Can you kindly PM me the email/username you used? I'll assist you further in private messages.

DrSwad I made it bro thanks

There's a small typo at the difficulty of a problem. It says difficulty: East

Fixed. Thanks for pointing it out.