For all to explore
Problems have been well tagged. You can search problems by their names, sources and tags. If you dislike them, you can still turn that off. There can be also task-oriented sources, with which students can easily find their school assignment on just one click.
There have always been complaints about the irrationality of the judge system, including the 'time limit exceeded' case which cannot be explained, and 'Presentation Error' becoming 'Wrong Answer' as a frustrating mistake. We are dedicated to solve such problems and special judges are used to prevent these kinds of mistakes from happening.
For all kinds of situations
Interesting OI Problems! Basically, you can submit your program and compete with others. OI Problems are graded according to test cases. It is even possible to gain some score when your algorithm is not completely correct.
Many traditional problems, based on standard input and output, using the rule of ACM-ICPC contest. You can practice your programming skills here. The verdict will only be Yes or No. Note that it is also widely used in college examinations.
Need any help? We hope this will solve your problem.