Welcome to UOJ $$$\Sigma^\ast$$$ Round #1 !

We are pleased to invite you to UOJ Σ* Round #1, which will be held on Sunday, April 13, 2025 at 17:00 (UTC+8).

There will be 3 problems with subtasks, and 5 hours for you to solve them under UOJ rules (similar to IOI, but pretests are used during contest rather than system tests).

UOJ $$$\Sigma^\ast$$$ Round is a series of contest held by CommonAnts on UOJ, thanks to everyone for your contribution.

In formal language, $$$\Sigma^*$$$ represents the set of "all" strings. Can you find the answer to the problem in the ocean of countless characters?

Contest Link

UOJ $$$\Sigma^\ast$$$ Round #1 is authored and prepared by CommonAnts et al, with difficulty at about $$$2100, 2800, 3500$$$ on Codeforces (I think so).

The top three participants and a special participant with condition of SHA256 48405573d9ac7a841e4860fab6036961bd8a2e7404027595e7a84b47c7771b6b will get our special gift.

PS. CommonAnts is now working on algorithms and computer science educational research, including competitive programming. Interested ones may contact us.

As seen, many tricks and some technics are found and used in Algorithmic Competitive Programming. They don't have enough academic value for lack of induction, abstraction, theory or application. But these are still of some use, especially for juniors and young students before entering university.

These materials are everywhere on the Internet, from blogs to contest tutorials. Maybe some of the below could help?

• An index for current important materials, organized by categories in CS and Competitive Programming.
• An electronic journal (like IOI's and CCF-NOI's) for these toys. (To take place of those boring training courses in college, maybe.)
• A global discussion platform (like AoPs or StackExchange?)

Please comment if you know any of the above existed.

I'm just discussing the probability :) Thanks!

One of my problems has a table(LaTeX tabular) in it, and Polygon is not able to translate it into HTML automatically. How to deal with it? Can I edit the HTML statements independently, or the only way is to change it into an image?

Contest Link

The night falls usually, while the street lights are shining;

The new year came quietly, with the bells of temples ringing.

The splendours and hardships of the bygones has faded away, rendering centuries of reality as transient as fleeting clouds;

And the uncertainties and probabilities of the future is yet to come, making the shared offing between you and me.

The Lunar New Year is here! Out with the old, in with the new, LibreOJ is holding a grand contest for the Year of Wuxu.

The round will be similar to a normal Codeforces Div.1 round in difficulty. We have picked some interesting ideas for this round, and partial-score subtasks will be available. We believe that all participants can get quite a bit from them.

The round will be held on IOI rules with no submission limit, the scores of different problems will be different.

Conventionally, participants have chances to get LibreOJ souvenirs. Good luck and have fun!

Detailed information on the round is as follows.

Basic Information

• Time: 22 Feb 2018, 18:00~22:00 CST (UTC +8)
• Duration: 4 hours
• Number of tasks: 6
• Rules: modified IOI rules
• Rated on LibreOJ

Tasks

Scores for individual tasks are as follows. Note that during the contest, the feedback will be given in percentages instead of actual values.

Contest Team

Problem Authors

• CommonAnts
• 613
• King_George
• choosemyname
• Serval

Testers

• flukehn
• consecutivelimit

Rewards

• The top four participants who haven't won the LibreOJ “Hello 2018” hoodie yet will get one.
• Additionally, one extra hoodie will be distributed among the participants by a secret rule. The UTF-8 encoded simplified Chinese description of the rule has an MD5 checksum of 8f1e90e2c37e64299e347f85356f3c3a. However, if the lucky one has already won the hoodie before, the prize will not be sent twice.

Sorry for my unnatural English.

Notes

• So far most of the contents (problems and announcements) on the site are in Chinese only, but the problems of this round will be available in both English and Chinese. As long as the menu bars are in English things are working well.

• The register email of LibreOJ is in simplified Chinese, but don't worry, you only need to click the link in it to complete your registration.

• You do not need to register for a contest on LibreOJ. Every submitter is regarded as a participant.