During March 2026, Y. Kim contributed to the DaleStudy/leetcode-study repository by developing two core utilities focused on algorithmic problem solving. Kim implemented a Two Sum Solver in JavaScript, utilizing a hash map to achieve O(n) time complexity for efficient index lookups, addressing the classic array sum problem. Additionally, Kim built a Duplicate Number Detector that leverages a hash table for rapid identification of repeated values within arrays. Both features emphasized performance and maintainability, with code reviewed for clarity and future reuse. Kim’s work demonstrated strong skills in JavaScript, data structures, and algorithm development, delivering targeted, reusable solutions.