Kimiyuki Onaka
Software Engineer
Japan
Summary
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Rockstar🎓
Top SchoolKimiyuki Onaka is a software engineer in Japan with 11 years of experience building robust back-end systems and full-stack tooling for competitive programming platforms and online judges. With an academic background in logic (BE and MEng from Kobe University), he combines rigorous mathematical thinking with practical engineering to improve test case generation, caching, and API performance. He has played key roles in well-known open-source projects like Library Checker, AtCoderProblems, and online-judge-tools, contributing to infrastructure, database indexing, and test frameworks that scale for large problem sets. Notable but less obvious is his focus on developer ergonomics—implementing ETag caching, type-hint fixes, and HTML parameterization to streamline generation and verification workflows. Colleagues rely on him for tightening performance bottlenecks and making complex judge systems more reliable and maintainable.
11 years of coding experience
Master of Engineering - MEng, Logic, Master of Engineering - MEng, Logic at Kobe University
Japanese, English
Stackoverflow
1reputation
0reached
0answers
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Github Skills (25)
algorithm10
caching10
postgresql10
online-algorithms10
python10
apidoc10
data-structure10
api10
sql10
database-design10
coder10
data-structures10
rust10
coders10
test-automation10
Programming languages (19)
Github contributions (5)
online-judge-tools/oj
Jan 2017 - Sep 2021
Tools for various online judges. Downloading sample cases, generating additional test cases, testing your code, and submitting it.
Role in this project:
Full-stack Developer
Full-stack DeveloperContributions:47 releases, 11 reviews, 1246 commits in 4 years 9 months
Contributions summary:Kimiyuki primarily contributed to the development and maintenance of the online judge tools, as demonstrated by the initial commit, which set up the project's foundational components. The user implemented various functionalities like sample case downloading, language selection, user submissions, and testing, indicating a comprehensive involvement in the development cycle. Further contributions include handling and parsing of system test cases, alongside adding the ability to guess problem URLs.
downloadingcasespythontestingjudges
yosupo06/library-checker-problems
Oct 2019 - Sep 2021
The problem data (Test case generator, judge's solution, task, ...) of Library Checker
Role in this project:Back-end Developer
Back-end DeveloperContributions:54 commits, 30 PRs, 108 comments in 1 year 11 months
Contributions summary:Kimiyuki primarily focused on improving the problem data generation and testing infrastructure within the Library Checker project. They implemented and refined caching mechanisms to optimize test case generation, making the process more efficient. Further contributions included addressing type hinting issues, expanding the test suite with new problems (e.g., `push_back_pop_front_all_composite`), and improving the overall robustness of the testing framework. The user also updated the problem for SWAG and integrated parameters into the HTML generation process.
test-datacheckeronline-judgetest-case-generatorproblem
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