prabowo's blog

By prabowo, history, 15 months ago, In English

Hello Codeforces community,

We are excited to invite you to TOKI KSN Open Contest 2021 — an online mirror contest for the Indonesia national olympiad in informatics. This national olympiad is one of the stages required for our students to qualify to represent Indonesia in the International Olympiad in Informatics (IOI). You may have seen our past open olympiads (2015, 2016, 2017, 2018, 2019, 2020) and you can check our past problems here.

The contest is similar to IOI: 2 competition days (+ 1 trial session), each consisting of 3 IOI-style (partial, subtasks) problems to be solved in 5 hours. The schedule is as follows:

Each contestant can select any 5-hour window within the time range to do the contest for each competition day. Each contestant may start the contest any time within the time range, by clicking the "start" button. The scoreboard will be hidden until the contest has ended.

All three contests are now available on TLX.
For more detailed information and rules, see our official website.

See you on the leaderboard!

UPD The official contest has ended, thanks for your participation!

The result of the open contest can be found on our website.

You can upsolve the problems here.

The editorials can be found in the contest link or upsolve link.

If you'd like to give feedback to the KSN Open, you may submit a response in this form.

We thank everyone who are involved:

We hope we can conduct the open OI again, and see you next year!

 
 
 
 
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15 months ago, # |
  Vote: I like it +52 Vote: I do not like it

Last year's problems were interesting to say the least! I cant wait to join the mirror this year!!!

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    15 months ago, # ^ |
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    Also, I wish a good luck to all official contestants and mirror participants. Although it's a competition, don't forget to enjoy the problems too. :)

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15 months ago, # |
  Vote: I like it +42 Vote: I do not like it

As an official participant in the actual olympiad, I'd like to wish good luck to both the official and mirror participants!

(Let's see how the problems will be this year....)

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15 months ago, # |
  Vote: I like it +24 Vote: I do not like it

Good luck to all mirror participants and to all official participants as well.

As an official participant, I am very excited. After 10 months of doing CP, the day is finally here.

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15 months ago, # |
  Vote: I like it +16 Vote: I do not like it

Good luck everyone, especially for the official participants !

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    15 months ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    As you are an official participant yourself, good luck to you as well ;)

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      15 months ago, # ^ |
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      Thanks, lets give it our best !

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15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

need day 0 editorial

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15 months ago, # |
  Vote: I like it +8 Vote: I do not like it

Will we be able to upsolve afterwards ?

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    15 months ago, # ^ |
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    Yes, you will be able to upsolve after the announcement of the official result. Editorial will also be available afterwards.

    This blog will be updated when those are available, so stay tuned!

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15 months ago, # |
Rev. 4   Vote: I like it +14 Vote: I do not like it

As the only participant who solved problem 2A during the contest, I found out that my solution to the problem is quite different from the official editorial.

Here is my solution:

Solution

Edit: Thanks for all the kind words from everyone who replied to this comment :D

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    15 months ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    orz orz orz orz orz

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    15 months ago, # ^ |
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    orz congrats for first place!!!

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    15 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Wow!! You're the only official participant who solved that problem, and using unintended solution, and u won the first place. Congraattsss!!!

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15 months ago, # |
  Vote: I like it 0 Vote: I do not like it

If you need more challenges for problem 1C, try these two additional subtasks:

  • $$$Q=2000$$$, $$$N=1200$$$, there are at most $$$3$$$ different materials;

  • $$$Q=2000$$$, $$$N=800$$$, there are at most $$$5$$$ different materials.