E869120's blog

By E869120, 7 years ago, In English

Dear Codeforces.
Today, I wrote about a mystery of Codeforces contest start time.

1 — Background

There are many codeforces users from many countries. In spite of this, recently I feel Codeforces contest time is too biased and it's difficult to participate or enjoy for some country. For example, Codeforces Round #434 started at 13:05 UTC, Round #433 started at 12:55 UTC and Round #432 started at 14:35 UTC. It have only around 3 hours difference between "the earliest of the 3" and "the latest of the 3".
This is also an answer of "why I wrote this blog".

2 — Codeforces Time Distribution Graph

First, to investigate actual codeforces time, I searched recent 100 contests time and made a distribution graph.



3 — Problem

Recently, I found that Codeforces Contest times are biased and they're difficult to participate for some people:

  • Around 9000 out of 30000 (30%) active users are difficult to participate because they're too late time. (China, Japan, South Korea, etc.)
  • Around 3000 out of 30000 (10%) active users are difficult to participate because they're too early time. (United States, Brazil, Canada, etc.)

For example, the standard time in Beijing is UTC+8, so around 65% of contest starts at 22:00 or later, and ends at 24:00 or later. A large amount of participants are students, and I think 24:00-03:00 is too late time for student. If they saw systemtest and rating change, the sleeping time could be one hour later.

The other example is in New York. The standard time is UTC-5, so around 95% of contest starts at 12:00 or earlier, and ends at 14:00 or earlier. I think it is too early time, and the time overlaps for most people because of school or working. They can wake up more earlier, but I think morning is busy time for the most, so it's difficult to make time to participate a single contest in morning.

4 — My Suggestion

I think it is better that codeforces do this:

  • ~20 or ~30 percent of contest should move in range 06:00-12:00 UTC. It's better time for Chinese, Korean, Japanese, etc. (It is also possible time for Indians, etc.)
  • ~15 or ~20 percent of contest should move in range 21:00-03:00 UTC. It's better time for American, Canadian, Brazilian, etc.

This system in my suggestion is like TopCoder. (Contest time is not too biased)

I think this made some good effects and bad effects as follows:
  • It became just a little bit more difficult to participate Codeforces contest for Indian, Russian, etc.
  • It became more easier greatly to participate Codeforces contest for Chinese, American, etc.
  • On the whole, I think active users would increase because it seems that there are many people who didn't cannot participate because of time.

This is just my suggestion, but I think this is also a strategy to increase users and to make codeforces more active.

Thank you for listening.
  • Vote: I like it
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7 years ago, # |
  Vote: I like it +106 Vote: I do not like it

Recently, I found that Codeforces Contest times are biased

you realized that only recently?

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    7 years ago, # ^ |
      Vote: I like it -26 Vote: I do not like it

    Sorry for sentence that easy to misunderstand, but I started codeforces 9 months ago. I thought 9-month is "recently" to see all 7-years codeforces history.

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      7 years ago, # ^ |
        Vote: I like it +40 Vote: I do not like it

      it's well-known fact that most of the contests start near 5-8 pm Russian time, also years ago the starting time was fixed for almost all the contests.

      I agree that it creates difficulty for some participants but many have already raised the same issue but admins seem want to put starting times in time that is comfortable for them so that they can monitor the contests.

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7 years ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

Well, I don't know about other countries, but in Japan:

  • Student has schools except Sunday (weekday 8:00-15:00, sunday 8:00-12:00)
  • Many people use trains to go to school, and average time to go to school is approx 1 hour
  • Assuming contest durations are 2 hours, 83% of the contest includes 24:00-5:00 or 7:00-17:00

But, why Japanese people are participating codeforces contests on weekdays, they reduce large amount of sleeping time, to participate Codeforces countests.
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7 years ago, # |
  Vote: I like it +27 Vote: I do not like it

For me it looks normal that time must be good for Russian people when site is Russian :) So I do not believe Codeforces team will increase amount of contests for other countries and decrease users from native country.

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    7 years ago, # ^ |
      Vote: I like it +14 Vote: I do not like it

    If 30% of active users live in Asia (as claimed in this blog), let's for the sake of argument assume that also 30% of problems have been set by people living there, as with 30% of blogs/comments. If they contribute 30% of the content, wouldn't it be kinda fair to make the contest timing easier for them once in a while?

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      7 years ago, # ^ |
        Vote: I like it +5 Vote: I do not like it

      I read blog and I am not sure that 30% of active users live there ( in Asia yes, but in countries with bad time zone I am not sure). For example lower than 7% registred users are from China, from Japan lower than 1%...

      Second thing, I agree than we should more contests 4-5 hours earlier ( like AtCoder time ), but TopCoder style only can decrease amount of participants.

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7 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Choosing a convenient day would also be helpful, it would be better if contests took place on the weekends, Sunday preferably.

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7 years ago, # |
  Vote: I like it +13 Vote: I do not like it

To be honest, we would need a survey to made any conclusions about the most suitable contest time. As a person who lives in Asia (UTC+7 now and UTC+8 back when I was in university), I actually prefer the current Codeforces contest time (starting at around 10pm to 12am) to AtCoder contest time (7pm).

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    7 years ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    I would say 14:00 UTC is the best for our timezone, since you have time to go out for dinner but not have to sleep so late.

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7 years ago, # |
  Vote: I like it +70 Vote: I do not like it

Meanwhile, on AtCoder...