Welcome to LCH::Ryu Online Judge — a small learning platform built by a programming teacher who also enjoys creating useful tools and learning through real projects.

The idea behind LCH::Ryu is simple: programming becomes easier to understand when you can learn a concept, practise it immediately, and receive clear feedback. This platform will grow gradually alongside new lessons, experiments, and things learned from building software in the real world.

If you are new to programming, start small and focus on writing correct, readable solutions before worrying about speed.

What you can learn here

• Build strong fundamentals with Python 3 or C++20.
• Turn lessons into hands-on practice instead of only watching or reading.
• Learn how to read verdicts, debug mistakes, and improve a solution step by step.
• Practise in a friendly space designed for curious, independent learners.

LCH::Ryu is not meant to be a race for the highest rank. It is a place to become a better builder, one problem at a time.

A little about me

Hi, I'm Ryu. I teach Python, build software and small tools, and enjoy turning difficult technical ideas into lessons that are easier to understand. I learn best by making real things, breaking them, fixing them, and then sharing what the experience taught me.

LCH::Ryu is one of those projects. It is both a place for my students to practise and a record of my own journey as a teacher and builder. I am still learning too, so the platform will keep improving as I discover better ways to explain programming and create useful learning experiences.

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.

Try these first problems:

• Even or Odd
• Solid Rectangle
• Solid Square

The loop-pattern collection is especially useful for practising nested loops and exact output formatting. Spaces and line breaks matter in drawing problems.

More explanations, programming lessons, and practical project notes will be added over time. The goal is to share knowledge that comes from both teaching and actually building things.

Useful links

• Browse all problems
• View submissions
• Check the leaderboard
• Report an issue

Community rules

Please help us maintain a friendly and productive learning environment:

• Do not spam comments or submissions.
• Do not misuse the issue-reporting system.
• Do not publish inappropriate content.
• Do not share solutions intended to bypass the learning process.

Be curious, practise consistently, and enjoy the process. Good luck and have fun! :3