Learn by solving.

Welcome to LCH::Ryu Online Judge, our private classroom practice space.

Use it to turn each lesson into hands-on practice and receive immediate feedback from the judge. Start with a small problem, write a clear solution, then learn from every verdict.

Recommended learning path

1. Read the problem statement carefully.
2. Identify the required input and output format.
3. Test your idea with the sample before submitting.
4. If your submission is rejected, open the result details and check the verdict.
5. Improve one concept at a time: conditionals, loops, arrays, strings, and algorithms.

Good first problems:

• Even or Odd
• Solid Rectangle
• Solid Square

For drawing problems, spaces and line breaks are part of the answer. If a submission is rejected, inspect its verdict before changing the code.

Be curious, practise consistently, and ask when a verdict is unclear. Good luck and have fun! :3