Hi Codeforces,

Many of you know about the CSES Problem Set, an online collection of over 300 competitive programming problems made by pllk! I have decided to clone all the CSES problems onto Codeforces! Each CSES category will be its own separate gym contest, listed below.

• Introductory Problems (19 problems)
• Sorting and Searching (35 problems)
• Dynamic Programming (19 problems)
• Graph Algorithms (36 problems)
• Range Queries (19 problems)
• Tree Algorithms (16 problems)
• Mathematics (31 problems)
• String Algorithms (17 problems)
• Geometry (7 problems)
• Advanced Techniques (24 problems)
• Additional Problems I (38 problems)
• Additional Problems II (39 problems)

There are two main reasons why I decided to do this project.

Slow CSES Judge

The CSES Judge is very slow, often resulting in correct solutions that should get accepted instead getting the TLE verdict. This is especially a problem for programmers who use Java. However, the Codeforces judge is much faster, which solves this issue.

Codeforces API

The Codeforces API is quite powerful. By adding these problems to gym contests, these problems can now be accessed by the Codeforces API, which will aid developers and people who use Codeforces bots to suggest problems.

Note: Work in Progress!!

This is still a work in progress! There are over 300 problems on CSES, and it will likely take me months to get them all on Codeforces. Therefore, I recommend you "favorite" this blog post, and check back on the contests regularly.

This is my current rating. As you can see, it says I am rated 2113. However, it also says I am a "Candidate Master", and my color is still purple!

This is my most recent contest. There are several things wrong with it.

• Its an educational round (rated for people <2100). If I was over 2100, why would it appeared in the list of my rated contests!

• The rating change listed was "0".

• Even though there was no rating change, we still see that my color changes from yellow to purple on the right!

MikeMirzayanov please take a look at this! This is probably an issue for many other people too.

Do You Want to Go to College? Are You Good At Writing Codeforces Rounds?

If so, then read on ahead! You will learn how quick and easy it is to go to college with the help of Codeforces!

College is Expensive.

The cost of MIT, a prestigious American university, is 53,790 USD per year. Even though scholarship is usually available, the average American student ends college with 37,000 USD in student debt! [Source] Student loan is also very pricey, with the average loan charging 5.8% interest per year. [Source]

However, Codeforces pays its problem setters big money! For a combined, Div 1+2 round, you can earn an average of approximately 400 USD. [Source]

Time Breakdown To Make a Round

Per Problem:

• 5hr to create idea, propose statement and solution, discuss with coordinator

• 1hr to write and revise statement, pictures, notes section

• 1hr to write and revise tutorial

• 1hr to write validator, checker, validator tests, checker tests

• 2hr to write model, alternative, and fake solutions

• 3hr to write generators for actually good test cases

• 2hr to make unexpected edits, changes from tester feedback

Per Contest:

• 8 problems per div1+div2 round.

• 50hr to come up with problem ideas that get rejected by coordinator.

• 30hr to discuss feedback with testers and coordinator, create announcement, editorial blog, answer clarifications during round, and any miscellaneous work.

Total Time To Write a Complete Round: 200 hours Assuming you work full time just problem setting (40 hours a week, 50 weeks a year), you should be able to write 10 high quality rounds a year!

Yearly Profit From Writing Codeforces Rounds: 4000 USD

How long will it take to pay off your student loan? Well, just run this quick python program to find out!

debt = 37000
year = 0
while debt > 0:
    interest = 0.058*debt
    debt -= (4000-interest)
    year += 1
print(year) #we get an answer of 14!

Conclusion: It Will Take 14 Years to Pay Off Student Loan Debt Via Codeforces

This of course assumes that you don't have to pay any other expenses, and problemset as a full time job. On the bright side, imagine what your rating would be after those 14 years...

Warning: This is satire. Please don't actually write 140 Codeforces rounds to pay for college. Unless you want top contributor spot.

Hello Codeforces!

What is Reaper?

Reaper is a math game all about timing, strategy, and patience. It was developed by folks at AOPs, and many games have been played on that site. How Reaper works is that whenever you reap, you get points equal to the current time and the time of the last person to reap. Additionally, there is a cooldown between reaps. Thus, the strategy is deciding when to reap. If you wait too long someone else might reap and you won't get your points. If you reap too quickly, you will get very few points which is very inefficient, due to the cooldown. Thus, you need to find the optimal time to reap, and also finetune your reaping strategy based on your opponents.

Standard versus Blitz Reaper

Standard Reaper usually has a long reap cooldown, usually in the range of several hours to a day. Thus, these games usually take days or weeks to finish, and require patience. Usually, standard reaper games have dozens or even hundreds of competitors! Blitz games are very different. They have very short reap cooldowns, usually around 10 seconds. Blitz games usually are very quick to finish, so players are recommended to continuously play from beginning to end! Although strategy is important in both modes, in Blitz reaper keeping track of your opponent's reap cooldowns is critical to success! Of course, the Red Crab Inn has complete support for both modes!

Inviting the Bot To YOUR Server

Setting up the bot is easy. Simply add the bot to a Discord server in which you are an administrator using the link above. Then, in any channel, simply type in $reaper. This will automatically create all the channels and roles the bot needs to function! That's it! You're done setting up the bot, and you can immediately move on to starting your first game!

Help

The Red Crab Inn bot supports many commands for optimal gameplay ease. At any point if you need help, simply type in help into the #reaper channel (created by the bot) to pop up the help menu. Of course, if you have any questions, concerns, or other queries please please direct message me on either Discord or Codeforces!

Source

All Reaper game code was written by me in Python, using the discord.py library, and hosted on repl.it. The idea for the game of Reaper is taken from AOPs. Check out the public github repository for more! If you find Reaper interesting, please share the bot with your friends!

Thank you for reading this article, and I hope you enjoy playing Reaper with friends!

Public Server

If you want to play on the Reaper Public Server, maintained by myself, click the above link.

1-gon's pleas for contribution have finally worked! As of Global Round 12, Monogon now has 205 contribution, beating Errichto's 204 contribution. Mike Mirzayanov of course doesn't count.

Let us celebrate Monogon's special day!

So, I noticed that there is a selection for the targeted division of a proposed Contest.

However, there is no way to propose a Div 3 round. How do you propose a Div3 round?