### rng_58's blog

By rng_58, 5 years ago, ,

I'm currently at the airport now, and I have some free time before boarding. Here's my prediction of this year's WF:

1. SPb ITMO
2. Moscow SU
3. U Zagreb
4. Tsinghua
5. MIT
6. U Tokyo
7. U Warsaw
8. Lviv NU
9. Shanghai Jiao Tong
10. Jagiellonian
11. SPb SU
12. University of California at Berkeley

After the contest, let's see if my predictions are good :)

• +287

 » 5 years ago, # |   +54 SPb ITMO Moscow SU U Tokyo Shanghai Jiao U Zagreb U Warsaw Lviv MIT Tshingua Jagiellonian U Wroclaw Carnegie Mellon University
•  » » 5 years ago, # ^ | ← Rev. 2 →   0 Nice to see U Wroclaw on your list but I hope we have strong chances to beat Jagiellonian this year. Even though piob is in a superb shape.EDIT: So, I was right. But sadly my dear friends finished 14th. Wroclaw haven't won any medal since 2005 when we had legendary team with gawry.
 » 5 years ago, # |   +38 I think that U Tokyo ( rng_58 team) will be top 3.
 » 5 years ago, # | ← Rev. 2 →   0 SPb ITMO U Tokyo Moscow SU Shanghai Jiao Lviv U Zagreb MIT Tshingua National Taiwan University University of Southern California U Warsaw Shanghai University
 » 5 years ago, # |   +3 Anyone willing to wager that ITMO won't be 1? :P
•  » » 5 years ago, # ^ |   0 I guess none.
•  » » 5 years ago, # ^ |   +214 Well, then they can't be second either, because Moscow typically takes that place.
 » 5 years ago, # |   +101 Uhm, everyone's prediction look so similar.. U Tokyo ITMO Zagreb Shanghai Jiao Tong Moscow SU MIT Tsinghua Warsaw Lviv Carnegie Mellon U Saratov Fudan
 » 5 years ago, # |   +60 I hope that MIT with ACube will get gold medal. They have strong team. SPb ITMO U Tokyo Moscow SU MIT Tshingua Lviv U Warsaw National Taiwan University Shanghai University U Zagreb Saratov State University Belarusian State University
•  » » 5 years ago, # ^ |   +22 Saratov go ahead!!!
•  » » » 5 years ago, # ^ |   +3 Saratov must win silver to keep our traditions!
 » 5 years ago, # |   -19 looking at everybody's predictions its like results are already out, ITMO is definitely winning!
 » 5 years ago, # | ← Rev. 2 →   +5 SPb ITMO Moscow SU U Tokyo Shanghai Jiao U Zagreb Lviv NU Tsingua MIT U Warsaw U Southern California Jagiellonian Sharif U
 » 5 years ago, # |   0 Any link for standing ?
•  » » 5 years ago, # ^ |   +3
 » 5 years ago, # |   +1 U Zagreb, who was in this team ? Anyone know?
•  » » 5 years ago, # ^ |   -7
 » 5 years ago, # |   +92 rng_58: So, your team competes against tourist's in 2013, then he doesn't compete in 2014 and neither did you. Now it is 2015 and you say your team will end up in 6th place and his in 1st. Let me laugh! In my opinion, you have prepared so much and your team will WIN this competition!
•  » » 5 years ago, # ^ |   +71 Well, in China we are told to be modest. I guess it is also true in Japan.
•  » » » 5 years ago, # ^ |   +89 Japanese competitive programmers (especially red coder) are tend to be TOO modest. Some of them believe that they are beginner. If they can solve a problem, they think that the problem was easy. If they can't solve a problem, they think they are dull. See TopCoder point allocation. rng_58 often underestimates his ability.
•  » » » » 5 years ago, # ^ |   +45 Just like some students in my school and university who say that they didn't study at all and expecting to fail the exam but end up getting the highest grade .
•  » » » » 5 years ago, # ^ |   +69 If they underestimate their abilities, then how they start solving problems from hardest on about every onsite event?))
•  » » » » » 5 years ago, # ^ |   0 and sometimes start solving the most interesting problem first
•  » » » » » 5 years ago, # ^ | ← Rev. 2 →   +65 Of course, they think they only have enough time to solve 1 problem, and other people will solve all problems.
•  » » 5 years ago, # ^ |   +15 Maybe he said that for decreasing the pressure
 » 5 years ago, # |   +68 eagerly waiting to see the fight between tourist and rng_58
•  » » 5 years ago, # ^ |   +11 I'd be really interested to know how these teams internally split up the solving and implementing tasks — given that there is some asymmetry that can't really be ignored.
 » 5 years ago, # |   0 SPb ITMO U Tokyo Moscow SU U Warsaw Tsinghua Shanghai Jiao Tong U Zagreb MIT SPb SU10.Jagiellonian 11.Lviv NU 12.University of California at Berkeley
 » 5 years ago, # |   +69 I'm surprised that no one predicted that Tapirs will win. I think, they have the highest chance to beat ITMO. Moscow SU SPb ITMO U Tokyo U Zagreb Shanghai Jiao Tong MIT Tsinghua U Warsaw Lviv NU Jagiellonian U Wroclaw SPb Academic University
•  » » 5 years ago, # ^ |   +87 Well, if check OpenCup, winter Ptz camp, and etc, we can see this chance is not very big. But they are cool on strange contests, and WF are always strange.
•  » » 5 years ago, # ^ |   +61 I guess people take into account "the curse of the 2nd place" for Moscow SU: many times various teams placed 2nd when there was a possibility to win world finals (in some of these cases, everyone was pretty sure that Moscow SU was going to win, and still they failed).However, this year the team believes they finally figured out the source of this curse: it is the color of their t-shirts (white+red) :) Now they switched it to the inverse of IFMO colors; we'll find out soon if their hypothesis is correct and the curse is broken.
•  » » » 5 years ago, # ^ |   +38 OK, apparently the problem wasn't t-shirt colors. Now Moscow SU should re-work their strategy from the beginning :)
•  » » » » 5 years ago, # ^ |   +17 Now when tourist is finally off the picture, I think they shouldn't change a thing :)
 » 5 years ago, # | ← Rev. 2 →   -18 Lviv Tokyo ITMO Waterloo Jagiellonian Zagreb Taras Shevchenko Kyiv NU BSEU MIT MSU Wroclaw Warsaw
•  » » 5 years ago, # ^ |   +45 Are you fan BSEU? :)
•  » » » 5 years ago, # ^ |   -41 The guys from BSEU did a lot to get to the finals, so, I think, they deserve to get silver medals. (=
•  » » » » 5 years ago, # ^ |   +54 Did they do more than other teams?
 » 5 years ago, # |   +141 Btw, someone ought to come up with a scoring formula so that we can crown a champion of this "prediction game".Here comes my predictions accompanied by some random comments which may be completely off (they are a stab in the dark after all) but reflects my gut feeling. Moscow SU — A strong team has gotten stronger. They seem to be in shape and I think they'll have the luck on their side. ITMO — On a normal day they would easily win, but my feeling tells me they'll unfortunately have some bad luck with their submissions. (And guessing them #1 is just too boring. ^^) Shanghai Jiao Tong — Chinese teams seem to always overperform and this team is good, so... University of Warsaw — Polish teams have the power to solve really hard problems (or "nice problems" as they call them). So I have a feeling that this team of 3 red coders won't be top 10 before the last hour, but will make a massive rush in the last hour. University of Tokyo — If Chinese teams tend to overperform, then Japanese teams tend to underperform in ICPC finals. On paper they are second, but the luck won't be on their side. I have a feeling they won't get any AC during the last hour. University of Zagreb — A 2-problem-win margin in CERC is impressive, but I think this team lacks the width required to smash in that extra problem. Fudan University — Chinese team with good top capacity can get you far. MIT — American teams tend to underperform as well, but this team got width and surwdkgo seems to be in great shape. Lviv National University — Sadly this team won't be able to keep their nerves in place and will thusly underperform. They will be top 5 during the first half, but then they will gradually lose it... Jagiellonian University — Does lack width, but piob will lead this team to a medal. Also, polish team, enough said. Peking University — The surprise of last year. Will they do it again? Well yes, but not to the same extent, though they'll get 2 AC in the last hour. KTH Royal Institute of Technology — Well not believing in your own uni is no fun so... Gullesnuffs (IOI 2013 Gold, IOI 2012 Bronze, IOI 2011 Bronze, IMO 2013 Silver, IMO 2012 Bronze), simonlindholm (IOI 2012 Gold, IOI 2010 Silver, IOI 2009 Bronze, IOI 2008 Bronze, IMO 2011 Silver) and jsannemo (IOI 2014 Silver, IOI 2013 Silver, IOI 2012 Bronze, IMO 2014 Bronze) make a good team with a lot of experience between them. They tend to solve a lot of problems early in the contest... and then just not solve anything at all. In NWERC 2014 they were in a massive lead (with 8 problems solved) after 131 min, and then they didn't solve anything more (a similar incident happened in NCPC 2013); luckily that was enough to qualify. If they overcome this bad habit they'll definitely be able to get KTH's first medal since 2010.
•  » » 5 years ago, # ^ | ← Rev. 5 →   +7 What about this scoring formula (for determining who wins prediction game): 10 * (number of correct medals) - sum(abs(prediction(team) - real_standing(team)) for team in prediction) Btw, it feels strange to me that you never participated in contest here, but sometimes appear to solve hard problems / give very insightful comments. So just our of curiosity, are you coach from KTH? :)
•  » » » 5 years ago, # ^ |   +32 I haven't thought much about your formula, but at least it seems better than number of correct predictions. Maybe we should add an upper bound to the points that can be subtracted in the second term? (I guess it's difficult to come up with a formula that is satisfactory in all situations.)Nope I'm not. I'm just a soon to be graduated student (I'm too old for ICPC as of this year) who's maybe a yellow (weak red on a lucky day) coder (I've participated in NWERC, NCPC, etc. with OK results). Though I've taught jsannemo one thing and another throughout the days (e.g. HLD, though he probably won't admit it ^^), so I guess I'm an unofficial coach. :P(And I always tell myself that I should start competing on Codeforces, but I never seem to get to it... =( )
•  » » 5 years ago, # ^ | ← Rev. 2 →   +29 Personally, i think SJTU in WF 2014 was not somehow overperformed''. Anyway, SJTU Dracrays is very different from SJTU Secret;Weapon. (They do have chance to overperform. XD)
•  » » » 5 years ago, # ^ |   0 Oh I see you were part of that team. ^^ Yeah you're right that SJTU didn't overperform in 2014 (I had guessed that you guys would be top 4!, too bad I can't find my predictions from 2014), though you didn't really underperform given your ratings. However, SJTU did overperform in 2013 (and probably also in years before that).
•  » » » » 5 years ago, # ^ |   +6 That's true. If I am getting right, my teams's CF ranking, TC ranking, and the final result are ALL #6 ...
 » 5 years ago, # | ← Rev. 2 →   +143 Lviv (slava Ukraini!) Kuiv NU (heroyam slava!) Tokyo (cause always exists asian man who does something better, than you) BSEU (just to troll tourist on 5th place) ITMO BSU (attracted by potato smell with 4th and 5th place) Kazakhstan NU Shanghai Jiao Tong U of Zagreb (COCI) Fudan (chinese everywhere) Odessa (hto nie scacha — toj moskal') MSU (klyati moskali) 14.Warsaw (Poland cannot into medals)88.Krakow (just for rzhaka)
•  » » 5 years ago, # ^ |   +38 Kuiv...
•  » » 5 years ago, # ^ |   +20 OK, tell me once again. Which country cannot into medals ( ͡° ͜ʖ ͡°)?
•  » » » 5 years ago, # ^ |   +57 Hmmmm...
•  » » » » 5 years ago, # ^ |   +11 All five CEPC teams in the Top20. IMHO, great result for the region. I supposed that Jagiellonian may go for silver because of their performance at Polish training sessions in May, but style of the problemset was different that most OpenCups and regionals used on this camp (somehow its close to BSUIR and Taganrog olympiad problemsets).
•  » » 5 years ago, # ^ | ← Rev. 5 →   +3
 » 5 years ago, # |   +1 SPb ITMO Moscow SU U Tokyo U Warsaw U Zagreb Tsinghua SPb SU Lviv NU Shanghai Jiao Tong Jagiellonian MIT University of California at Berkeley
•  » » 5 years ago, # ^ |   +7 The first three places right
 » 5 years ago, # |   -26 ITMO MSU Shanghai Tokyo Zagreb Tsinghua Lviv Warsaw Harvard Peking MIT Sharif
 » 5 years ago, # |   0 I almost forgot to predict...! ITMO UT MSU SJTU Zagreb Lyiv Tsinghua MIT SPb SU PKU Warsaw Singapore
 » 5 years ago, # | ← Rev. 3 →   0 ITMO MSU Tokyo Tsinghua Zagreb Shanghai MIT Lviv Warsaw UCBerkeley SPbSU Jagiellonian
•  » » 5 years ago, # ^ |   +18 You've posted Zagreb twice.
•  » » » 5 years ago, # ^ |   0 Edited. Saw it too late. I guess my prediction doesn't count.
 » 5 years ago, # | ← Rev. 2 →   +8 Which prediction has the most similarity to real standing?
 » 5 years ago, # |   +268 I am really excited about the number of people interested in the competition. This year I participated for the second (and last) time for Charles University in Prague (8th place, silver medal), which no one predicted to finish in top12.It was an unforgettable event, we were really lucky and consider the medal extremely valuable. Everything went well, all our solutions worked like a magic... I just wanted to share my personal experience and the strategy, which probably helped us a lot.We were quite underestimated because of our low Codeforces rating. Apart from me simsa.st is yellow and mirecek3 currently even blue. But on the other hand, they are great mathematicians (IMO gold medalist, etc.) and it proved to be crucial this year. During practice usually two of us coded, but after Dress Rehearsal we decided to change the strategy to "single coding monkey", which was me ;-) I didn't understand half of the problems, that I had implemented, they were just telling me what to write. It was incredible, we never tried this strategy before and it was an excellent choice (maybe combined with other factors as well).Fun fact: From our Central European Region (CERC) advanced 5 teams and we were the 5th advancing from the 8th place (3 teams from Warsaw and 2 teams from Zagreb ahead of us) -- same rank as in the Finals. We almost didn't qualify, but I am more than happy, that we did!Don't worry, you can still get a medal even if your team doesn't consist of three red coders.
•  » » 5 years ago, # ^ | ← Rev. 3 →   +24 Congratulations! That was really cool performance. This must be your strategy explained:Pair programmingAnd it probably explains why you had less bugs then usual. Going through these programming models with the team is probably coach's responsiblity, correct me if I am wrong.
•  » » » 5 years ago, # ^ |   +24 Thanks, our coach is responsible only for organisational issues. It is usually me, who organizes all tranings and prepare materials the others.
•  » » 5 years ago, # ^ |   +27 Thank you very much for sharing this.Was it hard for your IMO teammates to switch to ACM? Did they train a lot (coding / solve problems) or do the solutions just come naturally to them?At some moment, I really wanted to have IMO medalist in my team, as Math is usually our weak point, but I was afraid that unless they really spend effort, it's unlikely that they can solve anything other than pure math problems.
•  » » » 5 years ago, # ^ |   +38 Good question!One of my teammates (simsa.st) has a brozne medal from IOI as well and moreover he currently studies CS. For him it was easy to get used to ACM style.mirecek3 started participating in programming contest this very year (hist last undergraduate year) and he was the main brain of our team. The beginning (in September 2014) was really difficult, but in the end he managed to understand most of the basic algorithms and was able to design a solution based on them. He is still really bad in coding, but we somehow managed to combine our skills to this wonderful result ;-)Last time I participated in WF, it was 2012 Warsaw and my teammates were Mimino and k21. We were all quite strong coders, but probably missed a good mathematician.
•  » » 5 years ago, # ^ |   +8 Your strategy has been used by SJTU as I knew.
•  » » 5 years ago, # ^ | ← Rev. 2 →   +15 Congratulations for you awesome result!This year, our team (UP Catalunya, 37th place, angargo, drbioi and I) used the exact opposite of your technique (I was the 'thinking monkey', who thought strategy and algorithms, but wasn't allowed to touch the keyboard).Next year drbioi cannot repeat and we are doubting between transitioning to your strategy with angargo as coding monkey among other possibilities.I have 2 questions: What made you took the decision to change to 'single coding monkey'? To what degree were they telling you what to write? For instance, what do you mean exactly with 'I didn't understand half of the problems, that I had implemented, they were just telling me what to write'? Was someone by your side when you were coding or someone told you 'write maxflowmincost with those capacities and costs' and then you coded on your own? Thanks!
•  » » » 5 years ago, # ^ |   +79 I was the 'thinking monkey' too :)
•  » » » 5 years ago, # ^ | ← Rev. 2 →   +35 Hi, let me try to answer your questions: Changing the strategy was quite risky, because we never tried this before during a practice. Usually two of us were coding. But the last week I was in a fabulous coding form. I participated in several individual programming contests and I was fast and accurate as never before. I have absolutely no idea, how it has came to me, but before the competition, I was feeling really confident and proposed this strategy to my team. Because simsa.st was in the exactly opposite situation and nothing worked for him, they both happily accepted my proposal. Before the competition itself, I was quite nervous, because the coding man is usually the one who fails most, but the spirit fortunately persisted one more contest!! This one is a bit more difficult to answer. It really depends on the problem itself. Mincostmaxflow is not a good example, because I solved that problem by myself :-P Let me describe our cooperation on problem J. I had no idea what was the story about and they only told me to calculate a vector of divisors of numbers 1..N, and square it using FFT. Some of the problems were much easier to explain in detail together with the story itself. On the other hand, one or two problems, they were telling me the algorithm really in detail and I didn't know how it would look like in advance. It was like: "Read 4 integers" (I didn't know, what they meant), "Read N pairs and sort them, iterate through them, always take a difference and multiply it by this magic constant, then do this and that with them, ..."
•  » » 5 years ago, # ^ | ← Rev. 2 →   +29 I add my point of view.Firstly I am not a "pure mathematician" -- I sometimes code a game, for example nonogram solver or Fish Fillets Clone. I was just not a competitive coder but I liked coding. It perhaps explains my adaptability to the ACM.Secondly we are not just a randomly picked team -- we are organizing together a math competition for high school students or playing some night cipher games so we understand each other well. I heard that some universities does not want teams as "friends of fhlasek" but even such teams has apparently good chances for success :-)And about the ACM: Our original strategy was: "I am just thinking and fhlasek with simsa.st are coding." But after an individual training two days before the competition where I beated simsa.st (and fhlasek finished 5 times faster) we decided to fhlasek be the main coder (in fact simsa.st coded E on the finals).It was then even more comfortable for me when simsa.st didn't have to debug his code and could helped me with solving. So I understanded solutions of almost all problems which we solved except the problem A (I just knew it was something trivial and solved :-) ) When there were no problem solved, fhlasek were coding the problem M. So I understand why he describes himself as a monkey -- I explained him how to implement the only interesting part of it (MOVE command) and the rest is just routine following manual.A little weaker was coding of problem I -- it was so trivial that if fhlasek understanded it he would probably code it faster. Another interesting moment was when we one hour before end solved ninth problem. We were so suprised by it that we didn't have any other problem prepared. So after understanding the problem H fhlasek coded a ternary search for maximum of convex function while I was thinking which function should be used and how to handle multiple unknowns.P.S. I am purple again :-)