What about CSES?

 CSES (Competitive Programming) is a collection of algorithmic problems created by the University of Helsinki in Finland. The CSES problem set includes a wide range of problems covering topics such as dynamic programming, graph algorithms, and number theory. It's a great resource for practicing algorithmic skills and preparing for coding competitions.

The CSES problem set consists of over 200 problems, ranging from easy to challenging. Each problem includes a statement, input and output format, and examples. The problems are organized into different categories based on their topic, making it easy to find problems that focus on a specific algorithm or technique.

The CSES problem set also includes a leaderboard that shows the users with the highest scores. Users can submit their solutions to problems and earn points based on the difficulty of the problem and the speed and accuracy of their solution. The leaderboard provides an incentive for users to solve more problems and improve their algorithmic skills.

In addition to the problem set, the CSES website also includes a tutorial section that covers topics such as dynamic programming, graph algorithms, and data structures. The tutorials include examples and exercises to help users learn and practice new concepts.

The CSES problem set is a popular resource for competitive programmers and is frequently used in coding competitions and training programs. It's a great way to practice algorithmic skills and prepare for coding challenges, and it's completely free to use.