You all have noticed Last visit feature on profile page of every user. Me being a web developer is curious that how this feature is implemented on CF. As per my knowledge, CF website doesn't send background data to server while user is solving some problem.

Does this feature rely on the last time when user visited CF or reloaded any CF page?

I am thinking to implement same feature in one of my project but I doesn't want to use Ajax or any Asynchronous requests. That's why I am trying get idea regarding this feature's implementation.

MikeMirzayanov

This blog is dedicated to my hard working cheating scams exposures. These days trend has been setup to make blogs regarding cheating and exposes groups,websites which are center of cheating. Actually these exposures thinks that making these kind of blogs will help to stop cheating cases but actually it is doing inverse work. Let me explain with a story.

When the British ruled India, the city of Delhi was infested with cobras. To enlist the public’s help in eradicating the snakes, officials offered a bounty on cobra skins. Soon, however, a cottage industry of cobra farming sprang up. People were breeding them for their skins. The British paid out more and more money, but the cobra infestation did not abate. And cobra farming only added to the problem. When authorities finally got wise to the scam and withdrew the bounty, the farmers set their now-worthless cobras free. In this case, truly the road to hell was paved with good intentions – and cobra skins. 

This is called Cobra effect. In our case, we are dealing with cheating groups and sources instead of snakes. Cheating doesn't decrease with every blog exposing a telegram group , youtube channel or website. Instead, it increases the reach of these telegram groups and channels. Nobody knew early that cheating occurs on telegram groups or websites but after these exposing blogs, everybody came to knew about them.

In our story there is one major difference, there is no bounty on exposing cheating groups.

Hope you understand my point. Stop making these kinds of blogs. I you still make these blogs then start considering yourself on cheater's side as you will be helping them increasing their reach.

P.S. If you still don't understand then post blogs on some other places. I am fed up with cheating blogs of Codechef Contests on Codeforces.

I was trying to search for Range queries problems for practice and I found that CF problemset doesn't have "Range Query" tag.

Problemset has tags like:

• schedules — It has just 5 problems
• chinese remainder theorem — It has 12 problems

And few others which are too specific or rare like meet in middle, expression parsing.

I don't understand why these topics have tag but range query doesn't. Is there any specific reason behind it?