CompSciStuden
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How did people find the BIO this year? Did everyone find it hard because I certainly did. I was going to ask how people actually prepare for the BIO. If there’s any books or websites that they use to practice for it please.
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TSR Jessica
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Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.
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mqb2766
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(Original post by CompSciStuden)
How did people find the BIO this year? Did everyone find it hard because I certainly did. I was going to ask how people actually prepare for the BIO. If there’s any books or websites that they use to practice for it please.
As it's active until 15th Jan, it's not appropriate to discuss.
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_c0mputerphile
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It's over now! How much did everyone get?
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KevinIRoman
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(Original post by _c0mputerphile)
It's over now! How much did everyone get?
I only got 39, but I'm super proud of myself. It felt so good completing q1a and getting a few marks on q3a. I'm kind of disappointed that I wasted my time reading q2 (which is a question I had no idea how to do) than actually completing the 5 markers, especially the first 5 marker which I didn't have enough time to look at it thoroughly, but I think I found the solution minutes after finishing the paper. I hope the rest of you also had fun But I really want to know where I can learn how to do questions 2 and 3?
Last edited by KevinIRoman; 4 weeks ago
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CompSciComp-Temp
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(Original post by KevinIRoman)
I only got 39, but I'm super proud of myself. It felt so good completing q1a and getting a few marks on q3a. I'm kind of disappointed that I wasted my time reading q2 (which is a question I had no idea how to do) than actually completing the 5 markers, especially the first 5 marker which I didn't have enough time to look at it thoroughly, but I think I found the solution minutes after finishing the paper. I hope the rest of you also had fun But I really want to know where I can learn how to do questions 2 and 3?
An approach to question 3 was using a breadth-first search. Question 2 seemed particularly difficult this year, however.

Does anyone know what the threshold was for the second round?
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Nathan8520
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Does anyone know what the threshold is for this year? its been 2 weeks now and i havent heard anything and the website hasnt been updated with the first rounds problems. If anyone knows they have qualified then could you share your score so i know how far off i am.
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Spookiel
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Last year cut off was 74/100, although last years paper was significantly easier. I expect cutoff to be around 60 this year due to the difficulty of Q2. Highest in my school this year was 79 and I got 63. Hope this gives some measure of where you are at
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Spookiel
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(Original post by Spookiel)
Last year cut off was 74/100, although last years paper was significantly easier. I expect cutoff to be around 60 this year due to the difficulty of Q2. Highest in my school this year was 79 and I got 63. Hope this gives some measure of where you are at
(Original post by KevinIRoman)
I only got 39, but I'm super proud of myself. It felt so good completing q1a and getting a few marks on q3a. I'm kind of disappointed that I wasted my time reading q2 (which is a question I had no idea how to do) than actually completing the 5 markers, especially the first 5 marker which I didn't have enough time to look at it thoroughly, but I think I found the solution minutes after finishing the paper. I hope the rest of you also had fun But I really want to know where I can learn how to do questions 2 and 3?
Search British informatics Olympiad solutions into the web and some github repos will come up. Shamelessly plugging my own repo at Spookiel lol. It has solutions for pretty much all the Q3s and I’m working on explanations for them. I’m also working on putting together solutions for the round two problems.
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Nathan8520
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(Original post by Spookiel)
Last year cut off was 74/100, although last years paper was significantly easier. I expect cutoff to be around 60 this year due to the difficulty of Q2. Highest in my school this year was 79 and I got 63. Hope this gives some measure of where you are at
Thanks, this gives me hope that maybe there is a chance I will get through to the finals. What was your approach to Q3, I got full marks on it but my solution was very inefficient so I am thinking there is a better way.
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KevinIRoman
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(Original post by Spookiel)
Search British informatics Olympiad solutions into the web and some github repos will come up. Shamelessly plugging my own repo at Spookiel lol. It has solutions for pretty much all the Q3s and I’m working on explanations for them. I’m also working on putting together solutions for the round two problems.
Omg, I just want to thank you for your solutions! I looked at your solutions to prepare for this year's BIO, without them I probably would've gotten like 10 marks 😂. I still had a hard time understanding some of the solutions, because I literally never done such style of questions before. Thank you again! Btw, I'm wondering how did you learn to do such questions in first place? I understand that practice is key, but still, where/how did you learn the basics to do such questions?
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Spookiel
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(Original post by Nathan8520)
Thanks, this gives me hope that maybe there is a chance I will get through to the finals. What was your approach to Q3, I got full marks on it but my solution was very inefficient so I am thinking there is a better way.
There was a more efficient solution using Djikstra's, and this also allowed you to calculate the number of paths to a certain node. This was useful for part c and the approach I used. Although you can easily show that a BFS will pass comfortably as there are at most 8! = 40320 nodes, with each node having at most 3 edges, so ~120000 edges. With BFS running in O(m n) that is around 160000 operations, which passes comfortably in any language.
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Spookiel
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(Original post by KevinIRoman)
Omg, I just want to thank you for your solutions! I looked at your solutions to prepare for this year's BIO, without them I probably would've gotten like 10 marks 😂. I still had a hard time understanding some of the solutions, because I literally never done such style of questions before. Thank you again! Btw, I'm wondering how did you learn to do such questions in first place? I understand that practice is key, but still, where/how did you learn the basics to do such questions?
No worries, I'm glad my solutions helped. That was actually one of the main reasons I put them together online for people to find, when I started preparing for BIO, I couldn't find any solutions or explanations for most of the problems anywhere online. I learnt how to solve these sorts of problems mainly by just teaching myself recursion and dynamic programming concepts. Most of the trickier questions need memoized recursion or dp to solve them within the time constraints. Apart from getting familiar with dp and recursion, I would say the best thing to do is just think about the questions for quite a while. For example if you are spending less than 1 hour straight thinking about a problem, I wouldn't be surprised if the solution doesn't come to you. The problems are meant to be difficult and if most people could do them without much thought then there wouldn't really be a challenge involved. Personally I find the process of solving difficult problems very rewarding, so that motivated me to continue to try these problems. You also might have some luck asking your computing / IT teacher about these problems too, although I didn't have much luck with that myself. Let me know if I can clarify a particular solution for you by the way - I'm happy to help wherever I can.
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CompSciComp-Temp
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(Original post by Spookiel)
No worries, I'm glad my solutions helped. That was actually one of the main reasons I put them together online for people to find, when I started preparing for BIO, I couldn't find any solutions or explanations for most of the problems anywhere online. I learnt how to solve these sorts of problems mainly by just teaching myself recursion and dynamic programming concepts. Most of the trickier questions need memoized recursion or dp to solve them within the time constraints. Apart from getting familiar with dp and recursion, I would say the best thing to do is just think about the questions for quite a while. For example if you are spending less than 1 hour straight thinking about a problem, I wouldn't be surprised if the solution doesn't come to you. The problems are meant to be difficult and if most people could do them without much thought then there wouldn't really be a challenge involved. Personally I find the process of solving difficult problems very rewarding, so that motivated me to continue to try these problems. You also might have some luck asking your computing / IT teacher about these problems too, although I didn't have much luck with that myself. Let me know if I can clarify a particular solution for you by the way - I'm happy to help wherever I can.
Woah the legendary Spookiel himself - you and some other person called Matthewelse have helped so many of us. I'm planning on posting my own solutions, too.

As for learning the basics, trying problems and seeing how other people solve them is really useful. Maybe try the older BIO papers from the 2000s (they are easier).

I'm really sad I missed Question 2 since I'd found an approach that did work. I hope they release the thresholds some time soon. It's been nearly a month.
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KevinIRoman
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(Original post by Spookiel)
No worries, I'm glad my solutions helped. That was actually one of the main reasons I put them together online for people to find, when I started preparing for BIO, I couldn't find any solutions or explanations for most of the problems anywhere online. I learnt how to solve these sorts of problems mainly by just teaching myself recursion and dynamic programming concepts. Most of the trickier questions need memoized recursion or dp to solve them within the time constraints. Apart from getting familiar with dp and recursion, I would say the best thing to do is just think about the questions for quite a while. For example if you are spending less than 1 hour straight thinking about a problem, I wouldn't be surprised if the solution doesn't come to you. The problems are meant to be difficult and if most people could do them without much thought then there wouldn't really be a challenge involved. Personally I find the process of solving difficult problems very rewarding, so that motivated me to continue to try these problems. You also might have some luck asking your computing / IT teacher about these problems too, although I didn't have much luck with that myself. Let me know if I can clarify a particular solution for you by the way - I'm happy to help wherever I can.
Thank you so much for your help! I'll definitely start learning recursion and dynamic programming concepts for a start then, to hopefully slowly get the hang go of these questions. I also find solving these questions very fun and rewarding, and all I want is to someday be able to solve these sort of questions 😃.
You are extremely kind for offering so much help! I am way under your league, so I will firstly start from the basics and follow your advise. Honestly, Thanks again!
Last edited by KevinIRoman; 6 days ago
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Nathan8520
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(Original post by CompSciComp-Temp)
Woah the legendary Spookiel himself - you and some other person called Matthewelse have helped so many of us. I'm planning on posting my own solutions, too.

As for learning the basics, trying problems and seeing how other people solve them is really useful. Maybe try the older BIO papers from the 2000s (they are easier).

I'm really sad I missed Question 2 since I'd found an approach that did work. I hope they release the thresholds some time soon. It's been nearly a month.
You will never get the threshold, I emailed and apparently they never release it they just tell people if they made it through or not. Also they are probably waiting until they know if the finals will be online or not before they tell people if they have got through ( this is just speculation though ).
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Spookiel
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(Original post by CompSciComp-Temp)
Woah the legendary Spookiel himself - you and some other person called Matthewelse have helped so many of us. I'm planning on posting my own solutions, too.

As for learning the basics, trying problems and seeing how other people solve them is really useful. Maybe try the older BIO papers from the 2000s (they are easier).

I'm really sad I missed Question 2 since I'd found an approach that did work. I hope they release the thresholds some time soon. It's been nearly a month.
I’m honoured but really I’m just the same as you guys, I just wanted to give others a chance to look at solutions I couldn’t find when I was first learning.
I would definitely say some of the earlier BIO papers are much easier than the ones we get set now, although the finals are not too different I would say. To improve at these you definitely need to know how to solve many “classical” dp problems.

Q2 this year was particularly tricky, especially as debugging was nearly impossible with the triangular matrix.
Last year the boundaries were published on the 3rd of March, so we should be expecting them soon.
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Spookiel
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(Original post by Nathan8520)
You will never get the threshold, I emailed and apparently they never release it they just tell people if they made it through or not. Also they are probably waiting until they know if the finals will be online or not before they tell people if they have got through ( this is just speculation though ).
Actually the teachers who run the BIO for your school get told the boundaries if any students from the school qualify. Since we had one person qualify last year, we knew the boundary was 74. I’m also pretty certain a friend of mine will qualify this year as he got 79 by nailing Q2. I’ll let you know when I find out about the boundaries.
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Nathan8520
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(Original post by Spookiel)
Actually the teachers who run the BIO for your school get told the boundaries if any students from the school qualify. Since we had one person qualify last year, we knew the boundary was 74. I’m also pretty certain a friend of mine will qualify this year as he got 79 by nailing Q2. I’ll let you know when I find out about the boundaries.
Oh in that case i am sorry for spreading misinformation, i was just going of what the email i got said.
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Spookiel
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(Original post by Nathan8520)
Oh in that case i am sorry for spreading misinformation, i was just going of what the email i got said.
No worries, you’re right in that they don’t publish the boundaries on the website though which I find a bit weird
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