I'm glad to announce that we have today released a new version of the CSES Problem Set. It has many new problems and a new feature: hacking. You can access the problems here:
The problem set has now 200 problems — compared to the original problem set, there are over 100 new problems.
The problems are now divided into sections according to their topics, so it is easier to practice a specific technique. The last section contains more difficult problems that require creative problem solving skills.
There is a new feature: you can now hack submissions and improve the quality of tests.
After solving a problem, you can view the solutions by other users and try to hack them by giving a test case where the solution fails. If your hack is successful, the new test case will be added to the test data and all submissions will be regraded.
In the future, we will add many more problems, and our goal is to create a comprehensive problem set that has 1000 high quality problems. We will also gradually add model solutions that describe different ways on how to approach the problems.