Algorithm design

Writing algorithms is one of my hobbies. I first got into it while preparing for school competitions/olympaids and ended up taking classes taught by bruce . After that I did some more problems for fun.

Algorithm Contests

Contest Fails

This is really embarrassing…

• Codeforces Round #712 (Div. 2)

  Another round, another fst (at least I'm not a 2nd class citizen on AC server anymore woohoo)

• Riolku's Mock CCC

  We don't talk about this one.

• Codeforces Round #699 (Div. 2) Virtual

  We don't talk about this one.

• DMOPC '20 January Contest

  Didn't believe my own proof for p3

• DMOPC '20 October Contest

  Forgot how to implement classic matrix multiplcation

• Codeforces Round #675 (Div. 2)

  I'll fst my way to purple if I have to...

• Codeforces Round #632 (Div. 2)

  Double fst

• Codeforces Round #673 (Div. 2)

  FSTx2 + tried to bash lct on F

• CCC 2019 Senior

  s3

• CCC 2018 Senior

  Used float for S1

• And many more...

Problemsetting

Contests I set or tested:

• Codeforces Round #902 (Div. 1, Div. 2, based on COMPFEST 15 — Final Round)
• Codeforces Round 865
• Codeforces Round #831 (Div. 1 + Div. 2, based on COMPFEST 14 Final)
• DMOPC '21 September Contest
• Canada Day '21 Contest
• Codeforces Round (Div. 1 + Div. 2)
• Codeforces Round #706
• UTS Open '21
• Codeforces Global Round 9
• DMOPC '19 February Contest
• Codeforces Round #866 (Div.1, Div.2, based on Lipetsk Team Olympiad)
• Codeforces Round #857 (Div.1, Div.2, based on Moscow Open Olympiad in Informatics, rated)
• Codeforces Round #809 (Div. 2)
• Codeforces Round #742 (Div. 2)
• Codeforces Global Round 14
• Contest 2050 and Codeforces Round #718 (Div.1 + Div.2)
• Codeforces Round #706

List of my problems

Bonus problemsetting content

Resources

• Learning

  • USACO guide
  • Books:
    • Competitive Programmer’s Handbook by Antti Laaksonen
    • CP3
    • Introduction to algorithms
  • Codeforces resources:
    • Wide topic coverage but varying quality
    • Good Blog Post Resources about Algorithm and Data Structures
    • All the good tutorials found for Competitive Programming
  • Other
    • Algo Lectures by Errichto

  • Particularly good explanations of topics

    • Dominator tree
      • A&DS S03E04. Dominator Tree
    • Eertree
      • Eertree (or palindromic tree)
      • Short story about palindromes
    • Bitwise convolution
    • Link cut trees, euler tour trees
      • 19. Dynamic Graphs I by MIT OpenCourseWare
      • 20. Dynamic Graphs II by MIT OpenCourseWare
      • MIT video does not do rerooting, learn how to do that after you watch

• Practice

  • Problems
    • Herriot problem organizer
    • https://github.com/ac615223s5/tle codeforce bot
    • https://vjudge.net/ alternative submission and judge frontend
  • Contests
    • Atcoder
    • Codeforces
    • clist
    • dmoj
    • do virtual contests if live contests do not fit your schedule

• How to improve

  • All skill levels
    • usaco guide
    • Cp handbook/cp3 book
  • After finishing usaco guide gold (and completing most of the practice problems)
    • find a set of high quality practice problems and do random problems that are difficult for you
      • search on herriot
      • gitgud command on tle bot
      • directly searching codeforces or atcoder
      • other problem lists
    • do contests and virtual contests
      • codeforces, atcoder
  • Once you can solve problems 2100r or harder
    • read through some of the codeforces blogs and watch interesting videos for more knowledge on advanced algorithms if you want
    • Keep practicing more difficult problems
  • F.A.Q.
  • FAQ part 2

• Tools

  • Graph visualizer
  • Algorithm and template implementations:
    • https://github.com/kth-competitive-programming/kactl
    • https://github.com/bqi343/USACO
  • Algorithms reference
    • http://cp-algorithms.com/
    • https://www.geeksforgeeks.org/fundamentals-of-algorithms/

Other

My templates

Discord Server

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