During March 2025, Elavl developed a substring length constraint feature for the CodingTestStudy2/Daily_Morning_Coding_Test repository. The solution computes the maximum length of a substring where each character appears at most twice, addressing string-constraint validation for coding test evaluations. Elavl implemented an O(n) algorithm using Java, leveraging sliding window and two-pointer techniques alongside a HashMap to efficiently track character frequencies. This approach improved the platform’s throughput and scalability while maintaining code reliability and clarity. No major bugs were reported during this period, reflecting careful implementation and attention to maintainability in both code quality and documentation practices.