The Competitive Programming Initiative will be offering the Spring 2024 live bronze and silver courses!

Check out https://joincpi.org/classes for full details and to register!

Dates & Timings

• Bronze: Saturdays during Feb 3rd — April 20th from 4:00 PM — 6:00 PM PDT
• Silver: Sundays during Feb 4th — April 21st from 6:00 PM — 8:00 PM PDT

Classes will skip USACO weekends (Feb 17/18 and March 16/17)

Why should you sign up for our classes?

• The entire course costs $100 for weekly live classes, office hours, and access to our curriculum created by past USACO finalists!

• Financial aid is also available! If you apply, just know that we're generous when it comes to financial aid requests 😉

• There is a leaderboard system to incentivize friendly competition!

• Office hours on Zoom are offered twice every week, where students can personally ask instructors any question

Hope to see you in class!

The Competitive Programming Initiative

The Competitive Programming Initiative will be offering the Fall 2023 live bronze and silver courses! This will be the last semester before the 2023-2024 USACO season, so be sure to sign up if you wish to be thoroughly prepared before then!

Check out https://joincpi.org/classes for full details and to register!

Why should you sign up for our classes?

• The entire course costs $100 for weekly live classes, office hours, and access to our curriculum created by past USACO finalists!

• Financial aid is also available! If you apply, just know that we're generous when it comes to financial aid requests 😉

• There is a leaderboard system to incentivize friendly competition!

• Office hours on Zoom are offered twice every week, where students can personally ask instructors any question

Hope to see you in class!

The Competitive Programming Initiative

Hi!

The Competitive Programming Initiative is once again offering USACO Bronze and USACO Silver classes from April to May. We have limited space available, so be sure to sign up early! Financial aid is available for those who need it.

Each class consists of 9 two-hour lessons and accompanying homework, with a curriculum designed and developed by past USACO Finalists. We've streamlined our curriculum to cover all the material necessary to pass USACO Bronze or Silver by the December contest, so students can have the most time to practice and improve their USACO skills.

In order to ensure that all students have a strong understanding of the course content, we are also hosting weekly office hours where students will be able to ask instructors for help with that week's curriculum or homework, or just any problems in general that you needed help with

Beginner USACO Class

Time: Sundays, 1-3 pm PDT. April 2 to May 28
Purpose: Covers the techniques necessary to pass USACO Bronze
Prerequisites: Basic programming experience
Language: C++ or Java. Classes will be taught in Java, but instructors know both languages, so using either language is fine!
Topics Covered: See https://joincpi.org/classes
Learn More & Register: https://joincpi.org/classes

Intermediate USACO Class

Time: Saturday, 3:30-5:30 pm PDT. April 1 to May 27
Purpose: Covers the techniques necessary to pass USACO Silver
Prerequisites: Bronze-level concepts
Language: C++ or Java. Classes will be taught in Java, but instructors know both languages, so using either language is fine!
Topics Covered: See https://joincpi.org/classes
Learn More & Register: https://joincpi.org/classes

Office Hours will be held on Tuesdays and Thursdays from 5-6 PM PST over the semester

To view more information about our classes, visit https://joincpi.org/classes. You can also email us at classes@joincpi.org.

Sincerely, The Competitive Programming Initiative

Do you enjoy USACO? Do you want to help others discover the world of competitive programming too? You can volunteer for the CPI's USACO Classes and earn service hours while having fun teaching USACO!

https://joincpi.org/classes

Apply to become a CPI Class Instructor here: https://docs.google.com/forms/d/e/1FAIpQLSed_EHivwc1Z3LoaqQZhu813_3uNNousvN1QWmNt_q-6I6b8A/viewform?usp=sf_link

When?

Specific timings and dates are tentative as of now and will change and be finalized once the instructors are chosen. Currently, we are aiming at starting during the weekend of February 18-19.

Each class is comprised of 9 two-hour sessions. You don't have to be available for the full 9 weeks, though it is preferred. You can earn 3 volunteer hours per session (2 hour session + 1 hour prep time). CPI is a PVSA-certified organization, which means that the volunteer hours you earn with us can be used for the Presidential Volunteer Service Award.

Where does the money earned from classes go?

Hosting the USACO Forum, creating the USACO Guide, and filing the legal paperwork all costs money. All funds earned from classes goes towards supporting initiatives from CPI to further the world of competitive programming. None of the CPI staff personally profit from the classes. We also offer extensive financial aid -- Students who are unable to afford the classes can take it for free. In fact, 1/3 of our students from the first session received some form of financial aid (with the majority of these students getting access to these classes for free). Compared to other classes, CPI classes are some of the cheapest options available.

What's the Competitive Programming Initiative?

The Competitive Programming Initiative is a PVSA-certified nonprofit organization that aims to increase participation in competitive programming. One way we do this is by offering ultra-affordable competitive programming classes. We're also the team behind the USACO Guide and the USACO Forum.

Why should I teach?

Teaching at CPI is a great way to improve your teaching skills, earn volunteer hours, and give back to the Competitive Programming community! You will have the opportunity to help mentor the next generation of competitive programmers.

What are the requirements?

Typically, we require that Bronze instructors are in USACO Gold or higher, and that Silver instructors are in USACO Platinum (though this is not a hard rule). There will be a short application form and an informal interview process.

If you have any questions, feel free to comment below!

Merry Christmas and Happy New Year!

Do you enjoy USACO? Do you want to help others discover the world of competitive programming too? You can volunteer for the CPI's USACO Classes and earn service hours while having fun teaching USACO!

The Silver Self Study Course is very similar to the Bronze Self Study Course in terms of the format, however its curriculum will be based on both the Silver USACO Guide modules and the Silver Live Class curriculum

https://joincpi.org/video-classes

Apply to become a CPI Class Instructor here: https://docs.google.com/forms/d/e/1FAIpQLSed_EHivwc1Z3LoaqQZhu813_3uNNousvN1QWmNt_q-6I6b8A/viewform?usp=sf_link

When?

You can produce videos at your own rate, however there will be some generous deadlines set to speed up production of the videos. There is no set requirement of amount of videos to be produced, or hours of contribution per week, we simply ask that you make at least 2-3 videos, however you are allowed (and encouraged!) to make more if you want!

Where does the money earned from classes go?

Hosting the USACO Forum, creating the USACO Guide, and filing the legal paperwork all costs money. All funds earned from classes goes towards supporting initiatives from CPI to further the world of competitive programming. None of the CPI staff personally profit from the classes. We also offer extensive financial aid -- Students who are unable to afford the classes can take it for free. In fact, 1/3 of our students from the first session received some form of financial aid (with the majority of these students getting access to these classes for free). Compared to other classes, CPI classes are some of the cheapest options available.

What's the Competitive Programming Initiative?

The Competitive Programming Initiative is a PVSA-certified nonprofit organization that aims to increase participation in competitive programming. One way we do this is by offering ultra-affordable competitive programming classes. We're also the team behind the USACO Guide and the USACO Forum.

Why should I teach?

Teaching at CPI is a great way to improve your teaching skills, earn volunteer hours, and give back to the Competitive Programming community! You will have the opportunity to help mentor the next generation of competitive programmers.

What are the requirements?

Typically, we require that Silver Instructors are USACO Gold or higher, though this is not a strict requirement. There will be a short application form and an informal interview process.

If you have any questions, feel free to comment below!

Hi!

The Competitive Programming Initiative is once again offering USACO Bronze and USACO Silver classes from October to December. We have limited space available, so be sure to sign up early! Financial aid is available for those who need it.

Each class consists of 9 two-hour lessons and accompanying homework, with a curriculum designed and developed by past USACO Finalists. We've streamlined our curriculum to cover all the material necessary to pass USACO Bronze or Silver by the December contest, so students can have the most time to practice and improve their USACO skills.

In order to ensure that all students have a strong understanding of the course content, we are now hosting weekly office hours where students will be able to ask instructors for help with that week's curriculum or homework.

Beginner USACO Class

Time: Sundays, 4-6 pm PDT. October 9 to December 11 (skip November 27)
Purpose: Covers the techniques necessary to pass USACO Bronze
Prerequisites: Basic programming experience
Language: C++ or Java. Classes will be taught in Java, but instructors know both languages, so using either language is fine!
Topics Covered: See https://joincpi.org/classes
Learn More & Register: https://joincpi.org/classes

Intermediate USACO Class

Time: Saturday, 4-6 pm PDT. October 8 to December 10 (skip November 26)
Purpose: Covers the techniques necessary to pass USACO Silver
Prerequisites: Bronze-level concepts
Language: C++ or Java. Classes will be taught in Java, but instructors know both languages, so using either language is fine!
Topics Covered: See https://joincpi.org/classes
Learn More & Register: https://joincpi.org/classes

Office Hours will be held on Tuesdays and Thursdays from 5-6 PM PST over the semester

To view more information about our classes, visit https://joincpi.org/classes. You can also email us at classes@joincpi.org.

Sincerely, The Competitive Programming Initiative

Hi!

The Competitive Programming Initiative is once again offering USACO Bronze and USACO Silver classes from October to December. We have limited space available, so be sure to sign up early! Financial aid is available for those who need it.

Each class consists of 9 two-hour lessons and accompanying homework, with a curriculum designed and developed by past USACO Finalists. We've streamlined our curriculum to cover all the material necessary to pass USACO Bronze or Silver by the December contest, so students can have the most time to practice and improve their USACO skills.

NEW: In order to ensure that all students have a strong understanding of the course content, we are now hosting weekly office hours where students will be able to ask instructors for help with that week's curriculum or homework.

Beginner USACO Class

Time: Sundays, 4-6 pm PDT. June 26 to August 21
Purpose: Covers the techniques necessary to pass USACO Bronze
Prerequisites: Basic programming experience
Language: C++ or Java. Classes will be taught in Java, but instructors know both languages, so using either language is fine!
Topics Covered: See https://joincpi.org/classes
Learn More & Register: https://joincpi.org/classes

Intermediate USACO Class

Time: Saturday, 4-6 pm PDT. June 25 to August 20
Purpose: Covers the techniques necessary to pass USACO Silver
Prerequisites: Bronze-level concepts
Language: C++ or Java. Classes will be taught in Java, but instructors know both languages, so using either language is fine!
Topics Covered: See https://joincpi.org/classes
Learn More & Register: https://joincpi.org/classes

Office Hours will be held on Tuesdays and Thursdays from 5-6 PM PST over the semester

To view more information about our classes, visit https://joincpi.org/classes. You can also email us at classes@joincpi.org.

Sincerely, The Competitive Programming Initiative

Do you enjoy USACO? Do you want to help others discover the world of competitive programming too? You can volunteer for the CPI's USACO Classes and earn service hours while having fun teaching USACO!

https://joincpi.org/classes

Apply to become a CPI Class Instructor here: https://docs.google.com/forms/d/e/1FAIpQLSed_EHivwc1Z3LoaqQZhu813_3uNNousvN1QWmNt_q-6I6b8A/viewform?usp=sf_link

When?

Specific timings and dates are tentative as of now and will change and be finalized once the instructors are chosen. Currently, we are aiming at starting during the weekend of June 11-12.

Each class is comprised of 9 two-hour sessions. You don't have to be available for the full 9 weeks, though it is preferred. You can earn 3 volunteer hours per session (2 hour session + 1 hour prep time). CPI is a PVSA-certified organization, which means that the volunteer hours you earn with us can be used for the Presidential Volunteer Service Award.

Where does the money earned from classes go?

Hosting the USACO Forum, creating the USACO Guide, and filing the legal paperwork all costs money. All funds earned from classes goes towards supporting initiatives from CPI to further the world of competitive programming. None of the CPI staff personally profit from the classes. We also offer extensive financial aid -- Students who are unable to afford the classes can take it for free. In fact, 1/3 of our students from the first session received some form of financial aid (with the majority of these students getting access to these classes for free). Compared to other classes, CPI classes are some of the cheapest options available.

What's the Competitive Programming Initiative?

The Competitive Programming Initiative is a PVSA-certified nonprofit organization that aims to increase participation in competitive programming. One way we do this is by offering ultra-affordable competitive programming classes. We're also the team behind the USACO Guide and the USACO Forum.

Why should I teach?

Teaching at CPI is a great way to improve your teaching skills, earn volunteer hours, and give back to the Competitive Programming community! You will have the opportunity to help mentor the next generation of competitive programmers.

What are the requirements?

Typically, we require that Bronze instructors are in USACO Gold or higher, and that Silver instructors are in USACO Platinum (though this is not a hard rule). There will be a short application form and an informal interview process.

If you have any questions, feel free to comment below!

HMMMM...

Hey there, :)

Normally whenever I am working on a task requiring a segment tree or some similar data structure problem, and my code does not work, I find myself at a loss for what to do because it seems kind of hard to tell whether or not the segment tree is working properly or not...

I wrote this quick function to print a somewhat simple segment tree, but it feels rather ugly, and I don't think it would be feasible for more complex data structures.

void print_segtree(VI& segtree, string s = "") {
  int siz = (int)segtree.size();
  //0
  //1, 2
  //3, 4, 5, 6
  // 7, 8, 9, 10, 11, 12, 13, 14...
  cout << "Printing seg tree " << s << endl;
  for(int i = 0; i < siz; i++) {
    cout << segtree[i] << " ";
    if(__builtin_popcount(i + 2) == 1) cout << endl;
  }
}

Do you have any functions/scripts that you use to debug data structure problems, and if so, I would appreciate it if you would share it in the comments :p

Not including those much below your level, how many problems do you solve on your average day, and how much time do you usually spend solving them?

Hey there

I recently noticed that A2oj was back online after going static for a while, and I was excited to start using it again. However, when I was using the div 2. E ladders, after solving a problem, my ladder was not getting updated, but rather it stayed the same as before going static.

I just wanted to know whether or not this problem was happening to other people as well and not just to me.

Thanks in advance.

Edit: I just wanted to say that I updated my handle, logged out, and logged back in, left the ladder and rejoined it, and pressed the update button on the site, and it still would not update.

Hey there.

I was doing an A2OJ ladder, and I came across this problem (185C - Clever Fat Rat), that nobody had managed to pass system tests during the contests for some odd reason. When I went to check the editorial, there was no explanation, only a smiley face, so I decided to check the submission list, but I was not able to understand the code.

It would help me very much if someone could help me understand how to solve the problem. Thanks in advance.

I recently got into USACO platinum division and would like to try out lots of high quality problems. So far, I've completed USACO 2011 to 2019 Gold/Platinum problems.

Newer USACO Problems (2011+ ) Problem & Editorials http://www.usaco.org/index.php?page=contests ( 2011 onwards )

Now, I'm not sure what other problem sets to try. I've compiled possible candidates but want community opinion on quality of the problems from the list to optimize for learning. (Or suggest some other problem lists that i've missed)

a) Old USACO problems 2004 to 2011 Problems: http://tjsct.wikidot.com/usaco. (2007 to 2011) Editorials (Change Year # for other years) https://contest.usaco.org/OCT04.htm https://contest.usaco.org/OCT10.htm https://contest.usaco.org/NOV04.htm https://contest.usaco.org/NOV10.htm https://contest.usaco.org/DEC04.htm https://contest.usaco.org/DEC10.htm https://contest.usaco.org/JAN05.htm https://contest.usaco.org/JAN11.htm https://contest.usaco.org/FEB05.htm https://contest.usaco.org/FEB11.htm https://contest.usaco.org/MAR05.htm https://contest.usaco.org/MAR11.htm https://contest.usaco.org/OPEN05.htm https://contest.usaco.org/OPEN11.htm

b) Old IOI problems https://wcipeg.com/problems

c) Problems from Competitive Programming Handbook https://cses.fi/problemset/

d) Croation IOI https://hsin.hr/coci/

e) CP 3 ProblemSet https://cpbook.net/methodstosolve

Thanks

Hey guys!

I was having trouble solving milkvisits on the USACO gold contest. I solved it using heavy light decomposition, and I messed up on the implementation. I realize that you can solve this problem in a different, faster, and easier way, but I want to know what went wrong in my implementation. I looked at the test cases, but the smallest test case that I got a wrong answer on is of size 100, 000, so I had trouble visualizing the graph.

Here is my code, the input is in this google drive folder. I am supposed to output 1, but instead I am outputting 0. It would be of great help to me if you could tell me why my code is failing, and generally speaking, how you manage to debug problems with large inputs, if you use the inputs at all.

Thanks in advance.