The British Informatics Olympiad (BIO) is the UK's national computing challenge used to select students for the IOI, EGOI and WEOI. It is through this competition that I met most of my friends today. I feel privileged to have attended the finals twice, and as a result, represented the UK at the WEOI twice.
However, one issue I encountered during my first year of attempting this competition is the lack of helpful resources available online. There are a few YouTube video explanations, but for the vast majority of past problems from this competition, there are no editorials or model code.
That’s why I decided to create BIO Helper, a website dedicated to helping students prepare for both rounds of the competition by providing editorials and model code. With the help of many volunteers listed on the website (including, but not limited to, other BIO finalists), we now have a large proportion of Round 1 problems covered, along with a good number of Round 2 problems, with many more to come.
I want to share this site with as many people as possible so that more people can learn about competitive programming and find it easier to prepare for the BIO competition.
The website is relatively new, and we plan to add many features soon, including a grading system for Round 1. While there is publicly-available test data online, testing programs can be tedious, as it involves copying inputs, comparing outputs, and tallying points manually. Therefore, we plan to introduce a system where you can submit code, automatically receive your score, and see which test cases (if any) you failed. (Please note that in no way is this related to the official competition, during which participants will NOT be able to submit their code to be tested against any complete test data. This will just be a tool used for convenience during practice).
Finally, this project is open source, so if you find any bugs or have suggestions for improving the site, feel free to provide feedback by raising an issue on our GitHub.
Thank you for reading, and please don't forget to spread the word to those who you think may benefit from using this!
bo'ohw'o'wo'er!!!
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I'm a bit curious about the BIO R2 scoring rules in real contest.
The problem statements are not mentioning any subtask or partial score testcases. Is it revealed in actual contest, or the scoring still follow the old-fashioned way of number of passed testcases (maybe with hidden special property or size, requiring contestant to do their best in runtime efficiency)?
Also, do the problems have equal scores? Will easier problems have lower scores? Sometimes there will be another bonus problem, how will the problem be scored?
During the contest, there is a custom grader for BIO R2 problems. You are only allowed 5 submissions per problem. The feedback is also quite limited — here's an example:
Of course, many people ask what the difference between 'easy', 'medium', and 'hard' tests are, and there's no clear distinction, really. It's even possible that some 'medium' tests can have much higher constraints than some 'hard' tests. Sometimes test groups have different cases which your program might not have accounted for? But who knows, really.
Now for the scoring rules. Dr Forster, the team leader for the UK, repeatedly mentions that the number of full solutions is the most important criterion. All problems are worth the same amount, as well. So actually, even if you pass a higher % of tests than someone else, if you get fewer full solutions then it's viewed as less valuable.
Apparently, in the back there's some kind of hidden scoreboard which shows % of tests passed and number of full solutions, but it's not available for participants during or after the contest. In the two years I went to the finals, it was pretty easy for them to select the team because when ordered by full solves, the 4th person placed strictly higher than the 5th person. If there's a tie, one would assume at this point he might take into account the % of tests passed, and he's also mentioned that accuracy of submissions and clean code is also taken into account in this case. Basically, it's just discussed between the organisers and is up to them.
It's surprising to know that there is still a such black-boxed scoring rule and also contest feedback...
But at least they give 5 submissions.
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hi bort :))
I have another question about R1 cutoffs.
I have read some of the past problems, and I found the difficulty of the Q2 varies a lot: there may be "insanely" complicated Q2, or sometimes very simple. This problem seems significantly affect the participants' score distribution, or the cutoff.
I think usually (ideally) the R1 cutoff will be three programming problems (~75 points) add some writing problems, as a total of about 80~85 points. And it is a bit hard for even CF Masters (like me) to get a perfect score. But it's hard to say when there is some "imbalanced" problems.
Are there any public (or private) information about the cutoffs? Or any estimations? Are the difficulty provided by BIO-helper related to the actual (or guessed) cutoff?
P.S. In China some websites provide "cutoff estimation" feature before the official results are disclosed, where users upload their scores and the website gives an estimation according to the statistics. This may be interesting to BIO as well!
No cut-offs or any other information provided. The whole operation is conducted in as secretive and opaque way as possible. Scripts marked by teachers in schools by inputting test cases manually and locally. Questions are available for one month and the students can choose when to do the paper. There were rumours of cheating in R2 which provides the additional assurance that no one ever cheats in R1. Based on all that (or who knows what because nothing is transparent) 15 are invited to do R2 at the final camp. Probably the most ridiculous olympiad process anywhere in the world but remember no one can say that.
In fact, a little birdie told me somebody cheated in the 2024 R1 and scored 100/100. It was only discovered after they were invited and had already attended half of the camp.
Very much agreed, I think the organisation definitely needs some minor change and modernisation — however the quality of the problems is usually decent, barring some issues with too small time-limits.
As the birdie that told sagaboga that someone cheated in BIO, I can confirm that the number of cheating participants in 2024 BIO was a non-negative natural number.
There is no public information about the cut-off scores. Personally, I know that in 2024 it was 87, in 2023 it was 85, and in 2021 it was about 60-70 (Probably because Q2 was extremely difficult).
I agree that Q2 is often a deciding factor. Q1 is usually trivial/easy and Q3 is sometimes harder but pretty easy for anyone who's taken the time to learn BFS or Dynamic Programming (I think most experts and maybe even specialists can solve it). But Q2 is usually impossible to stress-test (there's no grader in R1, so you have to get it right on your first/only attempt) and the implementation difficulty varies a lot.
I think in the future, as the UK becomes stronger in terms of CP, the cutoff will probably stay in the high 80s or low 90s for all future rounds, unless the format changes and/or the questions are made more difficult.
The difficulty provided on our website is informed by around 7-10 R1 and R2 participants; it's not really based on any statistics (we have none). Sometimes we will disagree on a difficulty put forward by one person and we will change it.
The idea about the users uploading scores and the site estimating a cutoff sounds like a great idea! Hopefully by the time that R1 is finished ($$$\approx$$$ early january) we will have enough users to provide a meaningful estimation. Thank you for the idea.
Thank you for your information! Also thanks ag._.!
Wish the information could help the future participants. Maybe you should add the information on BIO-helper! Like USACO Guide has some unofficial insights from previous contestants, but they do provide some useful information.
I think that's a good idea as well! :)
I'm just curious — how come you are so interested in the BIO? Do you live in the UK? Or are you just curious how another national Olympiad works given that it's not really detailed anywhere online?
thx
Wish I had this last year!!
you have it now, get on the grind lol