HCSS Software Developer interview questions

Had a call with a recruiter and was given a take home assessment. On the call, the usual questions you would expect from an interview were given. The take home assessment was checking to if a given square was a magic square. I submitted the assignment with about 6 testcases showing that it worked. The only requirements given were to make sure that all sums equaled to the same number and that all values were unique, distinct from 1-n^2. I took a mathematical approach in checking that all values were distinct using the sum of natural numbers formula instead of unnecessarily iterating over the square to produce the most optimal solution. I also explained this in the comments. I was rejected saying that my solution did not meet the requirements listed in the document. I sent a detailed email back as to how my solution met the requirements listed in the document and an explanation, and never heard back. I don't think this is a very good reflection of the technical aspect of the company. I would have appreciated them letting me know they were expecting a different implementation rather that saying the solution missed requirements when it did not.