On main we have the tag, which after some googling seems to refer to a certain online grading/contest website (I must admit it is not entirely clear what the mission of the website is from a quick first glance). It seems that user(s) have been using the tag to denote questions appearing on that website.

Question Do we really need an SPOJ specific tag? Why would not do?

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    $\begingroup$ Re, question: nope, and contest-math is quite sufficient, methinks. $\endgroup$ Commented Jun 18, 2013 at 12:17
  • $\begingroup$ Too many FLAs already... $\endgroup$
    – copper.hat
    Commented Jun 19, 2013 at 18:24
  • $\begingroup$ @copper.hat what's FLA? $\endgroup$ Commented Jun 20, 2013 at 8:47
  • $\begingroup$ Four letter acronym :-). $\endgroup$
    – copper.hat
    Commented Jun 20, 2013 at 9:16
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    $\begingroup$ @copper.hat I propose UFLA for consistency - unidentifiable FLA... $\endgroup$ Commented Jun 21, 2013 at 14:20
  • $\begingroup$ (self-servingly) How would Brilliant.org tag fit in? The suggestion of online-judge doesn't really work. $\endgroup$
    – Calvin Lin
    Commented Jun 26, 2013 at 7:56
  • $\begingroup$ @CalvinLin: considering you don't even want Brilliant questions here, why would we bother having a tag for them? $\endgroup$ Commented Jun 26, 2013 at 7:58
  • $\begingroup$ From "what information tag conveys", the idea of the SPOJ tag (for the question) was to help identify such questions and encourage hints to guide thinking, as opposed to simply producing the entire answer. I think that this great, if it can be applied to Brilliant's problems too. $\endgroup$
    – Calvin Lin
    Commented Jun 26, 2013 at 8:04
  • $\begingroup$ @Calvin then what about just (contest-math)? $\endgroup$ Commented Jun 26, 2013 at 8:05
  • $\begingroup$ I would think that contest-math simply is a description of the type of problem. It doesn't convey that full solutions should be avoided. E.g. Putnam problems would be included under contest-math, but should not be discussed until the grace period is over. $\endgroup$
    – Calvin Lin
    Commented Jun 26, 2013 at 8:08

2 Answers 2


What is SPOJ?

For those who don't know, SPOJ is a website where users solve programming problems via submitted source code. In some instances, nontrivial mathematical knowledge is required to succeed. They have thousands of user-submitted problems. My impression is that SPOJ is intended largely for programming practice.

Why did I add a SPOJ tag?

I originally introduced the tag yesterday motivated by this question:

Given n girls and boys how many ways are there to arrange them such that any two boys have atleast 'k' girls between them.

where the author gave no mention to the fact that it was identical to a SPOJ problem (presumably copy/pasted from the site). Subsequently I added it to other SPOJ-related questions, largely for completeness.

It seemed, at the time, an obvious tag to add since there's a tag. This tag would have been helpful for me, and it didn't seem to be unhelpful for others.

What information does the SPOJ tag convey?

Judging from the SPOJ forums, they do not seem upset about helpful hints and remarks being available on the internet (in fact, they set up a forum for that purpose). They seem upset, however, if workable source code is available on the internet.

The idea of the tag is to highlight this to those who have encountered SPOJ before (and the tag wiki provides a link for those unfamiliar), and adjust their answers accordingly (if necessary).

Could there be a better tag?

I'm certainly not dead set that the tag should exist. But I feel these questions could use a tag.

Only in a loose sense would SPOJ be regarded as a "contest"; it would be comparable to saying that maths.SE is a "contest" to see who gets the most reputation. Nevertheless, I don't think it's wholly wrong to tag these questions , since it conveys the idea of where the problem originated.

An tag might be more appropriate, and this would encompass both and .

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    $\begingroup$ I'm supportive of the idea of an "online-judge" tag, to subsume spoj, project-euler, and any others that may arise (UVa, TopCoder, CodeForces, CodeChef, USACO, IARCS, whatnot). $\endgroup$ Commented Jun 18, 2013 at 18:41
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    $\begingroup$ I concur with @ShreevatsaR; earlier, I thought we could amend math-contest to cater for this, but indeed, that tag may lose too much coherence from such actions. However, the particular name online-judge nags me a bit; I don't like it too much. Perhaps online-challenge? I'd go with math-challenge but that's too close with math-contest. I bet that there are a good number of math-contest question that would be more aptly given the online-challenge tag. $\endgroup$
    – Lord_Farin
    Commented Jun 18, 2013 at 19:14
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    $\begingroup$ @Lord_Farin: I don't like the name all that much either, but "online judge" seems the standard name in the programming-contestant community for these things; the name SPOJ itself stands for "SPhere Online Judge". See also the UVa Online Judge at onlinejudge.org , the Timus Online Judge, and many many others... there's even (currently) a Wikipedia article called "online judge" that lists several of these. (Of course, you could argue we don't have to use the common name...) $\endgroup$ Commented Jun 18, 2013 at 19:34
  • $\begingroup$ @Douglas: thanks for posting this. I'll comment a bit more later. $\endgroup$ Commented Jun 19, 2013 at 9:34
  • $\begingroup$ Okay, reading through your answer and digging into @Shreevatsa 's Wikipedia link I think I can see the difference (though it doesn't seem to be too great) between online contests and online judges. I like the proposal of one tag to group (spoj) and (project-euler) and other online judge questions. I don't quite like the name (online-judge), but I don't have anything better to offer myself. $\endgroup$ Commented Jun 19, 2013 at 10:17
  • $\begingroup$ Since you say said question is a plain copy, including a backlink might be a good idea $\endgroup$ Commented Jun 21, 2013 at 14:23

This seems like a perfect candidate for elimination according to this question ("necessary evil", "generally discouraged").

Those adding the tag will almost surely write "SPOJ" somewhere in the question body, which to me strongly suggests that the tag suffices.

Perhaps it can be retained as a synonym, so as to prevent it from being created again, just like the tag.

So what about (which, according to a reasonably thorough search through the current tags, is the only remaining contest-type tag after will be gone)? Should we synonymize it with too?

If so, then I think there should be an edit to to expressly include online math (or math-related) contests as well.

  • 7
    $\begingroup$ Woah, hold on with undoing my tagging. One hour does not give much time to respond. The arguments presented here apply to thousands of other tags as well. Moreover, SPOJ is not actually a "contest". $\endgroup$ Commented Jun 18, 2013 at 14:13
  • $\begingroup$ @DouglasS.Stones My apologies; due to browsing the Unanswered tab, I was under the impression that five questions had been retagged, and only the last one remained (because there was only one unanswered spoj question). $\endgroup$
    – Lord_Farin
    Commented Jun 18, 2013 at 14:19
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    $\begingroup$ I believe (project-euler) is somewhat specific. Many people are hesitant to answer questions taken directly from Project Euler. More details can be found in the tag-wiki. $\endgroup$ Commented Jun 18, 2013 at 14:54

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