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What- Problems Lists Created by Dr Mostafa Saad Ibrahim (mostafa.saad.fci@gmail.com)

- These are the private problems lists for supervising my trainees for ICPC / Online Contests / IOI.
- I am releasing for the public in hope making trainees training much more efficient and effective

- Note: If you are a beginner, there is well-organized roadmap for a better start for you [links in end of page]
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Latest Version
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Audience- Training for online contests, ICPC or IOI
- Searching for problems with specific categories
- Tired from 'automatic tools for ranking problems by difficulty'
- You train a lot but many problems are not that interesting or have duplicate ideas
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My Relevant
UDEMY courses		Coupons
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Mastering 4 critical SKILLS using C++ 17
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Mastering critical SKILLS in Data Structures using C++
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Mastering 4 critical SKILLS using Python
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Mastering critical SKILLS for Algorithms in C++
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Mastering critical SKILLS for Cracking Coding Interviews
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BackgroundDuring my weekly meetings with the PhD supervisor, I was inspired by launching an online program that I named Supervision. Instead of the coaching style, my major role as a supervisor was to assign problems in the trainee sheet. My goal was to assign problems that match the trainee level and enhance weak skills. As I don’t have to help technically in solving problems, and I don’t believe in the importance of that, I had much more time to supervise ~225 trainees. This gave me a unique opportunity to accumulate a huge amount of statistics and useful information from trainees about the tackled problems (~25k submissions). The program started in 2016 for Egyptians, in 2017 for Arabs and for international students since 2018.
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Outcomes of supervisionBased on the received feedback from my trainees, I used to refine my vision for this program. I ended up with 2 big lists of problems: one for guys training toward IOI and another for ICPC/OnlineContest styles. Specifically 4 critical features:

Problem difficulty level [1-10] per problem is a manual weighted average of the assigned levels from my trainees’ sheets. A common complaint about 'online tools/ways for ranking problems by difficulty' is that they are not accurate. The issue is more severe for OI problems.

Problem importance level: ~ 5 levels (important, very interesting, interesting, good, normal/boring/repeated). Trainees solve a lot of problems that many of them are repeated or boring ideas. To maximize the training outcomes, one should train on unique/interesting ideas much more. Something that most of us can’t figure out easily.

Editorials. Many interesting problems may not have editorials (or have hard to understand editorials). I used to ask trainees to write some summary of how they solved a problem. Circulating these editorials between my trainees made it easy for them to get problems solved.

Submissions info: In Trainees Submissions page, ~25k submissions of my trainees. Per problem info (status, submissions count, times for reading/thinking/coding/debugging, category, subjective level, and a comment. You may use it to know some details about how others performed with the solved problem.
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Problem LevelIn column C, you will find the problem diffculty. I tried to rate a problem relative to CodeForces levels as following:

CF-Div2-A => 1 - 2
CF-Div2-B => 1.5 - 3
CF-Div2-C => 3 - 5.5
CF-Div2-D => 5 - 6.5
CF-Div2-E => 6 - 7.5
CF-Div1-D => 7 - 8.5
CF-Div1-E => 8 - 9.75

As a fact, I did not solve most of the problems. My trainees did for many of them. Based on that, I tried manually to put a level for the problem. Since the middle of 2018, all my trainees found most of the problems of the right level relative to their skills. I can say this column now is accurate to some extent.

To what degree you can trust it? In columns G and H, how many trainees tried to solve the problem and how many ones of them couldn't solve it. The more trainees solved the problem, the more accurate the measure. A problem with empty numbers means no one solved it. I used some online measures to do the early estimation but never assigned to a trainee.
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Problem Importance- In column F: 5 different values for importance from P5 to P1 ((important, very interesting, interesting, good, ok, normal/boring/repeated). The empty value is unknown or normal.

- Sometimes you find value v. E.g. v2. This is a variance indicator to indicate a kind of variance in difficulty for trainees when solving this problem. You may ignore it

- Important note: let's say someone is doing well in Div1-D problema (e.g. his level is 7.5). He selected a problem of P5 (important) & level 6. He will solve it fast and probably find it a normal problem. On the other side, if someone who is good in Div2-D (e.g. his level is 5.5), he will find the same problem very interesting and a must to solve a problem.
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Problem Category- In Categories page, you will find a lot of specific categories. Use the [id] to search in the sheets for a specific category
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How to train- There are 2 lists: General (For ICPC & Online Contests) and another for IOI training

- For each list, there are 2 copies: one for problems sorted by the category (then by level, then by importance). Another sorted by level.

- I used to train my trainees by level. If the trainee's level is 6.5, I sample problems of level 6.25 to 6.75 of P5/P4/P3 ratings.
- A good distribution might be as following:
-- 10% problems below your level: for speed training and confidence
-- 20% problems at your level: for sharpening coding skills
-- 60% problems slightly above your level: for growth
-- 10% problems way above your level: to remind you that the path is still long and to give you more fresh ideas
- I recommend to think up to 60-120 minutes, then check out the editorials. For 10-20% of your problems, you 'may' try up to 3-4 hours
- I am totally ok that they don't get most problems by themselves as long as they can solve them using editorials eventually

- Even if you don't target IOI, many OI problems are worth solving. Many trainees found them much valuable.

- How to know your level?: Investigate your offline solving skills in Codeforces. E.g. If you can solve in 2 hours Div2-E problem, then your level is ~6.5

- 7+ is a hard level in the sheet.
- Note, there is also another view for IOI by contest, where problems are grouped by the contest itself. This should help you figure out the popular topics in this contest.
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Help improve the content- Found a dead link or a comment on a specific row, right click on row and select comment from the menu
- Wrote an editorial for a relevant problem? Put it on online (e.g. ur Github). Insert comment with link
- If people misused the comment feature, I will have to disable it.
- Have a suggestion? Enhancement? Email me (mostafa.saad.fci@gmail.com)
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Other relevant resources by me
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Arabic Youtube Channel for competitive programming
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English text of the channel on github
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IOI/OJs official solutions/Mini-Editorials in a single repo
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Training roadmap for newcomers
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Training Individual Sheet
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Video: Psychological Concerns in CP
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History of my Supervision
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More about me
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Acknowledgement: I would like to thank all the trainees who was part of this program. Without them, such lists will never exist.
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Top Contributors in the supervision (my assigned problems + their own additions; AC or not)
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#submissions (AC+!AC) - Name
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981 MohamedNasser
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844 MagdyHassan
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811 MariamAlshereef
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752 StefanDascalescu
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537 AbdelrahmanMounir
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494 MohamedBakry
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459 WilliamLin
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433 UtsavRajpara
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428 AhmedSamir
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388 MoahmedEmad
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378 LucioCardoso
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352 AhmedHussnien
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332 AymanSalah
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331 MohamedAhmedNabil
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304 VasilevDaniil
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299 yazanAlzebak
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297 MichaelMounirFathi
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276 AhmedRamadan
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267 TranLoc
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267 AhmedGamalAbdelzaher
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262 NikolaPesic
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262 ZeyadKhattab
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252 MohamedAnany
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251 NathanWang
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248 AmrAhmedMaghraby
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247 OmarSaleh
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243 LtifiMohammed
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235 EldarUrmanov
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230 Engy
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226 NguyenTanbao
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226 HosamEissa
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221 Heshamsellat
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213 ShashankYadav
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212 AmrMohamedHosny
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212 AliHamdi
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204 AmrHassan
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191 MohamedTahan
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189 WaleedAbdelhakim
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189 PranavJangir
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189 Pongsaphol
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178 AhmadMadany
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178 YoussefElSayed
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176 MosabFathy
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173 SchwinnSaereesitthipitak
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160 MahmoudAli
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158 MiguelMini
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157 AliMagdeHafez
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154 AndiQu
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154 AbdullaAshraf
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149 AhmedIbrahim
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146 SaraElkady
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143 KhalidRamdan
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138 AbdalrhmanZboon
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137 ViktorKozhuharov
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136 HugoGarcia
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132 Omarkharouba
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132 Ildar
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128 ViktorLucic
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128 KhalidKee
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128 MinaAmirSadek
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127 Hosamkamal
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123 AhmedZaher
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121 RahulGoswami
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119 HelikThacker
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115 OssamaHatem
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112 WalidSadallah