zoj

ZOJ, short for Zhejiang University Online Judge, is an online judge and problem archive used for competitive programming and programming education. Operated by Zhejiang University in China, it provides a platform for submitting code and receiving automated feedback. Problems cover a wide range of topics and difficulty, and the site hosts practice sets and contests.

Origin and scope: ZOJ was launched in the late 1990s to support computer science education and programming contests at Zhejiang University and beyond. It has since grown into a widely used resource for practice, contest preparation, and examination readiness.

Platform and features: The system allows users to submit solutions in multiple programming languages, including C, C++, Java, and Python, among others. Submissions are compiled and run against predefined test cases, yielding verdicts such as Accepted, Wrong Answer, Time Limit Exceeded, Runtime Error, and Compilation Error. The site maintains user accounts, stores submission histories, and provides a public problem set with search and filtering options. A ranking component highlights top solvers and activity.

Usage and impact: ZOJ is one of several online judges used by students and instructors worldwide. It is commonly employed for self-study, course assignments, and training for programming contests, alongside other platforms.

See also: Online judge; Competitive programming.