Laggy's blog

By Laggy, 2 months ago, In English,

A series of unfortunate events has been going on for a few days since I moved to Innopolis, Russia. First, a nuclear explosion upon my arrival. Then the a small fire in the dorm I am staying at which lead to alarms firing and me running around in my pajamas while carrying only my laptop (Yes, I had to save one thing). And then I login to codeforces to find my contribution has decreased. Well now that's bad.

So as continuation for last year's blog here is some data from the handles we have of IOI participants.

Total Score Distribution

Day1 Distribution

Day2 Distribution

Bonus

Try to find tmwilliamlin168 in those pictures since Benq is obvious.

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By Laggy, 6 months ago, In English,

Asking for a friend.

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By Laggy, history, 8 months ago, In English,
Rank Country or Region University Member1 Member2 Member3 Team Rating
1 Russia Moscow State University LHiC V--o_o--V V--gLaSsH0ldEr593--V 3441.929
2 USA Massachusetts Institute of Technology xyz111 ecnerwala ksun48 3336.429
3 Japan The University of Tokyo sigma425 maroonrk yosupo 3118.398
4 Poland University of Warsaw Radewoosh Chameleon2460 oxytocyna 3059.272
5 South Korea KAIST ko_osaga alex9801 .o. 3003.474
6 China Nanjing University AceSrc gisp_zjz zyb 2846.168
7 Russia Moscow Institute of Physics & Technology amethyst0 AndreySergunin irkstepanov 2838.887
8 United Kingdom University of Oxford geniucos fanache99 atatomir 2795.429
9 USA Harvard University waterfalls Franklyn_W pbt17 2794.578
10 China Tsinghua University JOHNKRAM shigule ufo 2789.604
11 South Korea Seoul National University khsoo01 kdh_9949 namnamseo 2777.071
12 China Peking University rxdoi Altria-PenDragon Remilia-Scarlet 2769.395
13 North Korea KimChaek University of Technology black_horse2014 kutengine ksi1996 2759.542
14 Russia St. Petersburg ITMO University PoDuReM josdas romanasa 2718.51
15 Iran Sharif University of Technology M.Mahdi SeyedParsa LiTi 2697.8
16 Canada University of Waterloo --d Xylofo iburinoc 2689.332
17 Poland University of Wroclaw yarek Anadi MicGor 2688.16
18 USA Stanford University desert97 ericxu0 yum 2684.367
19 China Fudan University Gromah abc473848880 wxy_z 2681.779
20 Hong Kong The Chinese University of Hong Kong nhho hohomu jasonyik 2679.574
21 China Beihang University iwatani ShinriiTin Gengar 2671.088
22 United Kingdom University of Cambridge aitch Zoli9 lamejeck 2657.106
23 Japan University of Tsukuba nuip hugeh0ge reew2n 2651.845
24 Russia Saratov State University BledDest Roms adedalic 2647.698
25 Croatia University of Zagreb DBradac IvL valkyrie 2640.221
26 USA Columbia University vlecomte aditya1495 volz.kz.g 2622.478
27 Russia Ural Federal University Madball Programmer007 Apollon76 2599.683
28 China Shanghai Jiao Tong University Nisiyama_Suzune mxh1999 sun_en_ze 2588.669
29 India Chennai Mathematical Institute rajat1603 AnonymousBunny DP99 2569.625
30 China Zhejiang University lsmll jiangshibiao lzw4896s 2563.214
31 Syria Syrian Virtual University RedNextCentury BayHarborButcher kingofnumbers 2562.916
32 Belarus Belarusian State University of Informatics and Radioelectronics Z38 hloya_ygrt rui-de 2560.671
33 Brazil Universidade Federal de Pernambuco tfg luucasv diogo 2538.303
34 Germany Technische Universität München lumibons Gregory fleimgruber 2531.001
35 Russia National Research University Higher School of Economics qoo2p5 super_azbuka grphil 2525.348
36 Italy Scuola Normale Superiore cip999 fram Delfad0r 2515.252
37 India Indian Institute of Technology — Kanpur yashChandnani Gravito12345 Beast_Within 2500.223
38 India IIIT-Delhi Cerberus97 polingy Sullipopa 2498.967
39 Taiwan National Taiwan University johnchen902 nonamefour0210 wangyenjen 2489.748
40 Belarus Belarusian State University Lollipop kimden greencis 2488.162
41 Kazakhstan Kazakh-British Technical University Aeon NurlashKO Zharaskhan 2471.697
42 Vietnam Hanoi University of Science and Technology quang ladpro98 _T-T-T_ 2461.77
43 India Indian Institute of Technology — Kharagpur evil666man 0ogway chenghiz 2455.558
44 Serbia University of Nis — Faculty of Sciences and Mathematics ivan100sic vucislav lazar96 2446.165
45 Russia St. Petersburg Campus of Higher School of Economics afedor Eran IgorL 2435.055
46 USA University of Illinois at Urbana-Champaign BenZ TiChuot97 pittoresque 2429.617
47 Spain Universitat Politècnica de Catalunya metatron OneStone cescmentation_folch 2429.176
48 Canada University of British Columbia paulll brandonzhang miseri 2428.9
49 India Indian Institute of Technology — Madras teja349 pranav0123 raja1999 2426.346
50 Indonesia Universitas Indonesia ayaze DigiM IgoRamli 2426.232
51 Estonia University of Tartu loomas SLLN -is-this-fft- 2423.741
52 Japan Kyoto University joisino 2417
53 China East China Normal University ultmaster kblack zerolin 2415.697
54 India Indian Institute of Technology — Roorkee spj_29 deva2802 abhikalpu_123 2390.193
55 Argentina Universidad Nacional de Córdoba — FaMAF ec24 mrz MarcosK 2388.094
56 Egypt Faculty of Engineering, Cairo University OmarHashim Deathly_Hallows Momentum 2386.771
57 Brazil Universidade de Sao Paulo — Campus de Sao Carlos samuelfgs LoppA nonsequitur 2386.729
58 Kazakhstan International IT University Tima LeMans NaughtyMorzh 2386.675
59 Bangladesh Bangladesh University of Engineering and Technology _Ash__ Arg_007 t.muttaqueen 2385.583
60 Egypt Faculty of Computer and Information Sciences, Ain Shams University TripleM5da OreWaFujimiNoKeeDaaa Abdelrhman_Akram 2385.093
61 USA Duke University a142857a 2381
62 Brazil Universidade Federal de Campina Grande arthurCF emiso gugabribeiro 2377.993
63 Romania Alexandru Ioan Cuza University of Ia?i Juve45 Cristian1997 Sin 2376.103
64 USA The University of Texas at Austin masonsbro mIXs ryanr1230 2365.304
65 USA University of Southern California Rating2333 Shizuo anmtcel 2360.012
66 USA University of Central Florida SecondThread AuroraGarden blockingthesky 2358.529
67 Latvia University of Latvia Pakalns bauldaiselemaitre Ingus 2357.222
68 Switzerland ETH Zürich TimonKnigge 2351
69 Russia St. Petersburg State University andrey.zavarin AgReB fadeeva.kate.22.03 2349.01
70 Brazil Instituto Tecnológico de Aeronautica splucs leaomatheus LucasS 2349.001
71 China Nanjing University of Science and Technology Grunt henryrabbit starry2024 2343.901
72 Mexico Escuela Superior De Computo Instituto Politecnico Nacional Marckess galloska alaneos777 2341.837
73 Taiwan National Chiao Tung University ss1h2a3tw cthbst harryoooooooooo 2341.353
74 Brazil University of Brasilia Nson Lius rchehab 2337.465
75 New Zealand The University of Auckland UoA_ZQC sadobson97 sheepmolester 2331.001
76 China Southeast University, China CoupDeGrace Aguin fifteen 2326.765
77 Egypt German University in Cairo aabdelzaher Omar_Morsi Kharouba 2317.972
78 China Beijing Normal University MisakaKuma Forever_you zhuaiballl 2310.678
79 China Zhongshan (Sun Yat-sen) University mosfjh africamonkey 8300590 2308.04
80 Iran Amirkabir University of Technology ParsaA Arpa taxman 2302.605
81 Lebanon American University of Beirut, Faculty of Arts and Science Antoine remyels rayan.94 2290.11
82 India Indian Institute of Technology — Patna equinox i_love_Equinox gear4 2283.129
83 Argentina Universidad Nacional de Rosario brimix__ mredigonda indexs 2280.348
84 Singapore National University of Singapore btzy bayweiheng sidhant 2268.502
85 China Xi'an Jiaotong University zbh2047 I_love_Dayo_Wong Luffbee 2262.371
86 USA South Dakota School of Mines and Technology lrvideckis mdpfeifer 2261.756
87 Ukraine National Technical University "Kharkiv Polytechnic Institute" vlad8 NegaTeeF Cyber 2250.058
88 Egypt Cairo University — Faculty of Computers and Information compiler_101 eagle93 wewark 2247.502
89 Bulgaria Sofia University ha1vanka Viktor_Terziev pepi_angelov 2233.97
90 USA Carnegie Mellon University supasaya bluepichu Strikeskids 2226.55
91 Egypt Faculty of Engineering- Mansoura University Omar_Elawady abdulla.ashraf sara_elkady 2221.156
92 Syria Damascus University Nooor I-Love-Islam RamiZk 2205.201
93 India Indian Institute of Technology — Bombay superman_k pratyush1019 evilbuggy 2204.992
94 Cuba Universidad de La Habana blacktools yagamil albexl 2202.17
95 Vietnam University of Engineering and Technology — VNU dthangnguyen19 lazyc97 Slumdog 2196.313
96 USA Drexel University duyboy135 sampriti 2193.699
97 Iran Shahid Beheshti University AminAnvari mrm_196 Erfan.aa 2193.43
98 China South China University of Technology yang12138 ying971101 Mappy007 2180.628
99 Syria Al-Baath University Daniar waow ghostwarrior 2180.096
100 Mexico Instituto Tecnológico Autónomo de México Saat Juanito98 2177.082
101 Mexico ITESM Campus Monterrey eidan EliasMera Diegogrc 2176.332
102 Colombia Universidad Nacional de Colombia — Bogotá -osdajigu- mavd09 .vr 2142.54
103 Russia Northern (Arctic) Federal University Svenny ijnhtrgdew Artichoke 2130.763
104 Peru Universidad Nacional de Ingeniería — FC racsosabe valgt Fischer 2117.675
105 Mexico Instituto Tecnológico Superior del Sur de Guanajuato sggutier OrlandoIsay Thanya_Leif 2102.864
106 China Guangdong University of Technology Maplesss yang825641085 john123741 2087.697
107 Brazil Instituto Militar de Engenharia laderlappen samuraiexx rebecacalazans 2086.898
108 Indonesia Bina Nusantara University hantansu98 AVM.Martin ekeitaro 2058.737
109 China Northeastern University (China) lby2014 2052
110 Bangladesh Shahjalal University of Science and Technology ovis96 mk_Shahriar Jubair_2147483647 2048.825
111 Argentina Universidad Tecnológica Nacional — Facultad Regional Santa Fe lsantire matramos reaper703 2041.859
112 Argentina Universidad de Buenos Aires — FCEN teofr aborgna_ aradunsky 2019.769
113 South Africa University of Cape Town moyamo Saitama 1996.631
114 China Harbin Institute of Technology HIT_TOM 1996
115 Syria Higher Institute for Applied Sciences and Technology fresher96 1991
116 Cuba Universidad de Oriente — Sede Antonio Maceo ernestico yuriao yordanlp 1988.188
117 Syria Aleppo University SmokeOut ThePhenomenal watheq 1975.026
118 Colombia Universidad de los Andes, Colombia limboguard SparklingRa1n jdanielfandino 1831.698
119 USA University of Wisconsin — Madison sengi Assancious divide_by_zero 1752.581
120 USA University of Nebraska — Lincoln ptnk_1215_panaka_13 1736
121 Portugal Universidade do Porto gonp 1724
122 Egypt The American University in Cairo Ramenkami johnsourour johngamal 1642.854
123 Russia Moscow Aviation Institute ZimakOleg 1533
124 USA Colorado School of Mines 1
125 USA Princeton University 1
126 USA University of Chicago 1
127 Georgia International Black Sea University 1
128 Australia The University of New South Wales 1
129 Australia The University of Western Australia 1
130 Netherlands Leiden University 1
131 France École Normale Supérieure de Paris 1
132 Lebanon Lebanese American University 1
133 Japan Waseda University 1
134 Costa Rica Tecnológico de Costa Rica 1

Ratings updated on: 4/1/2019

Leave a comment if you know the remaining teams so we can have a complete list.

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By Laggy, history, 10 months ago, In English,

MikeMirzayanov First of all, thanks for the new feature. I was hoping you could add a new entry similar to the problem.points to the api response of the problemset.problems method. Surely, the new feature can be used to make interesting things like a smart problem selector relative to one's average difficulty.

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By Laggy, history, 12 months ago, In English,

Since ACPC is coming up and we have Teams participating in ACPC 2018 I used my api wrapper to build the table below:

Rating Sums

Спойлер

Codeforces Style

Name University Country Members Codeforces Team Rating
Aurora Princess Sumaya University For Technology Jordan Hiasat Motarack Light 2498.20620502827
RadioaActive SVU Syria JoudZouzou Tomah4wk kingofnumbers 2438.0314185839
AKA AKA FCIS Ain Shams University Egypt KhaledKEE TripleM5da Abdelrhman_Akram 2415.27692693251
One More Time Cairo University — Faculty of Engineering Egypt OmarHashim Deathly_Hallows Momentum 2391.60337777421
kalamantina Princess Sumaya University For Technology Jordan bugzzii 1am Mohammad_kilani 2234.36626643917
IOI - Egypt mohammedehab2002 Osama_Alkhodairy mahmoudbadawy 2230.30623382918
One For All FCI- Cairo University Egypt compiler_101 eagle93 wewark 2163.43894039428
e^x Damascus Universuty Syria Mohammad_Karttomeh Moaz.e M.Al-Hussein.96 2162.51336312017
Unexpected American University of Beirut Lebanon Antoine remyels rayan.94 2158.75815986223
Shalabi (unofficial) Tishreen University Syria massoud8032000 repeating Hasan 2086.86204119503
Team Sky Jordan University of Science and Technology Jordan Vendetta. Ownography abo_od303 2039.00938880022
BuzzKill FCI — Cairo University Egypt OsamaFathy omar23 alimagde 2027.71199163576
IOI (unofficial) - Jordan SuperJava Muhanad_AlWarareh Mohammad_Alaa_Alwarareh 1990.84568248118

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By Laggy, history, 13 months ago, In English,

Hello beloved community, today I am happy to present you codeforce's contest picker which is a public version of our internal community's picker that can be read about here.

This is a continuation of CPC (Competitive Programming Community) project that you can check out in my older blogs.

What does it do?

It's simple, you add a list of handles and it will pick you all the contests that none of the handles had tried (submitted, not necessarily accepted) before.

Gym is now included:

Since ICPC is near, I decided to include gym contests since you guys probably want to do them with your teams? I hope I was right.

Normal rounds are also included:

Right at the top of the website you see Virtual Contest Picker.

Searching works.

Both Virtual Contests / Gym Pickers have a search bar that filters the list using some string. If you want to do past ACM regionals with your mates you can just type ACM in the search-bar and it will show you ... contests whose name contains ACM.. obviously.

Usage:

1- Visit our website (below).

2- Choose your picker.

3- Add a list of handles.

4- Choose the contest.

5- Solve the contest.

6- Go to ICPC.

7- Beat Um_nik and his team.

Step 6 and 7 are optional. Jk, 1 to 5 are the optional.

Pick a Contest


Spoiler

Credits: Laggy BasselBakr

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By Laggy, history, 13 months ago, In English,

Hello Codeforces, hope you're all doing great. So while thinking about doing some projects related to competitive programming I came to the conclusion that I need an api wrapper to smoothen the process out and went and created one. It's unofficial meaning it's not approved by MikeMirzayanov yet (approve pls?) and I hope it becomes a community project that who ever wants to contribute feels free to do so.

What can it do?

My initial vision was creating something that automates certain processes e.g. hacking, selecting problems based on some data and basically anything that has to do with statistics of contests/problems.

For example, this is how I found that the only C problem that has fft as a tag is 662C - Двоичная табличка
Pretty cool, right?
Another simple use case is that pulling out similar statistics becomes very easy:

IOI 2018 Score vs CF Rating

Codeforces Progress Statistics

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By Laggy, history, 13 months ago, In English,

Total Score Distribution

Day 1 Distribution

Day 2 Distribution

This data was generated using 214 contestants whose codeforces' handles were available at the IOI statistics profile and using CF API Wrapper (which will be released tomorrow) to generate CF data.

Can you guess which point is Benq? ^^

Bonus:

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By Laggy, 19 months ago, In English,

As a desperate Pupil I was interested in knowing some more about grand masters and decided to look if any once-newbies besides zscoder have made it to red.

Insanely Dedicated People

User Minimum Rating Maximum Rating Δ
zscoder 1117 2908 +1791
netman 1105 2625 +1520
Arthur 1158 2592 +1434
Shayan 1119 2498 +1379
duyboy135 1098 2467 +1369
sillycross 1182 2540 +1358
senek_k 1084 2430 +1346
SmallBoy 1165 2462 +1297

So yes, 8 people made it. I don't know if that tells you anything if you're a newbie. But don't lose hope just yet.

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By Laggy, history, 21 month(s) ago, In English,

Had you ever thought about doing some contests virtually with your teammates or friends? If you had then, you know how hard it could be to find a contest that none of you had attempted. Well, not anymore.

The Virtual Contests Picker gives you a list of 6 random contests (if available) that a group of handles had never attempted.

This is part of the algo-chan project (Know more about it from this post)

How does it work: You need to type in the chat !cf vc div1/2 0 "handle1 handle2 handle3...".

Because every group has certain needs you can limit the contests to div1 or div2 and you can choose the minimum number of problems that should be included in the contests.

So the general syntax is:
!cf vc div min_count "list of space separated handles"

How to use:

  • Refer to the link above.
  • Join the server.
  • Use the command explained in this post.
  • Profit.


Right now it supports all codeforces contests except gym. But rest assured, gym will soon be supported. Hopefully in a few days.

I hope you like this little addition to the server and if you have any suggestions for this or for a new feature just let it out.

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By Laggy, history, 22 months ago, In English,

Hey guys, I am working on a virtual contest picker as part of the algo-chan project. I am trying to use http://codeforces.com/api/problemset.problems to build a problem list for each contest but this won't work because of contests with more than one division only the appended problems show there.

Example: ContestsL 872,871,870 870 seems like the base for the other two but there's no way to know where the other two start. For 872 the api doesn't even know about it's existence.

I hope MikeMirzayanov or anyone who has experience with doing something like this could help. PS: I am trying to use the API and not parse every codeforces.com/contest/id page. (Keeping this as a last resort)

Thanks in advance.

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By Laggy, history, 2 years ago, In English,

 Problem: 467C - Юра и работа So as you can see this is so cool because the bug doesn't actually have anything to do with the solving function. It happens somewhere when building the prefix sum. The current code doesn't pass TC#5 while after removing the green part it goes up to TC#55. How? I wish I knew. Maybe you guys have some thoughts ^^

Kudos to BasselBakr for playing with it.

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By Laggy, 2 years ago, In English,

CPC or Competitive Programming Community is a Discord server targeting problem solvers and competitive programmers from all backgrounds and different platforms.

First let me briefly introduce Discord for those who haven't heard of it before:

Discord is an all-in-one voice and text chat application that works on browser/desktop/phone. Every server can have multiple text & voice channels accessed by members of the server or limited to a certain group of these members. You can share code/text/links/pictures at the text channels and you can talk in the voice channels.

Why should you join the server?

Basically, you get to meet other members and have group discussions without caring about down-votes. The server is currently active with over 700+ members (still have a long way to go). Also, Discord has nice features such as pinning messages/pinging users/search function and many other cool stuff.

But most importantly, for all you contest enthusiasts, you will be very interested in joining our post-contest discussions. Those are when the server is most active and everyone is raging about their hacked solutions, bugged code, how they misunderstood the statements and/or all your typical post-contest feelings then, you discuss problems.
The members are from all ranks and A LOT of them are actually quite humble and love helping others. Well, you will know what I am talking about once you join wink.


Join Us by visiting this invite →
Share discord.gg/algorithms with your friends for good luck

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By Laggy, 2 years ago, In English,

tl-dr version of the problem: You have a set of numbers and you need to look for a subset with a sum that ranges from l,u given that u — l is bigger than or equal the difference between the max,min elements from the set of given numbers.

Why does the two pointer method work here? Sorting the numbers and just adding the elements until you get over the range boundaries then subtracting until you get it right (in case there's a solution this will always work), why? What's the logic behind it?

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