We continue to train the brain. We add competitions

Six months ago, I wrote a post about my interest in exercises for brain training , which resulted in a small site with such exercises , created for all who wish to embark on the path of cognitive enlightenment. Since the site was made with an eye on desktop games and applications, it turned out to be in essence such an application only on the web. But recently it was decided to correct this little flaw and add some kind of interaction between the users of the site, in the hope that this will give someone additional motivation for training. The first thing that comes to mind is of course the competition system.

Horizontal split

At first there were attempts to find a third-party service that could be quickly bolted, but all I found was sharpened for casual games with a simple system of a single table of results and a pinch of achivok. I also wanted to separate users by skill from the box (a fairly standard practice, for example, in games such as LoL and SC2), because if there are a hundred people involved, then obviously someone will be in the hundredth place, and it may not feel very comfortable , looking at the top ten with the results many times more than him. Therefore, we need a mechanism for the division into smaller groups of equal strength. As a result, I had to write myself.
I didn’t think too much and seek out some ingenious algorithms for this task. If we need to break up into homogeneous groups, then we get the standard cluster analysis problem, take the k-means algorithm and get a partition. The only problem that arises here is that too good and too bad results can snap off a whole group. We also go from simple and we rank this task to a known problem in statistics, the problem of detecting outliers, we take the simplest algorithm to find them, and before using clustering, we cut off these results and automatically assign them to the best and worst group.
Total, we have horizontal splitting. Further, the system could be improved by adding a vertical partition, which would solve the problem of too many identical results. That is, instead of having one group with the results 1 1 1 2 2 2 3 3 3, it would be better that there were three equal groups 1 2 3, 1 2 3, 1 2 3. But since there are not very many participants yet, and the problem is not so acute, it was decided to postpone this modernization until better times.

Format

The static list from the top seemed to me less interesting than the constant updated one, so the format of the weekly competitions was chosen. And since training brings the greatest benefit when they are regular, it would be nice to somehow stimulate a person so that he would go to the site the next day and try with new forces, so it was decided to update positions and leagues once a day.

In total, this is not such a tricky system. Take part and leave feedbacks.
ru.brainexer.com/contests.html
www.brainexer.com/contests.html