I started with a phone call with an HR representative. They told me about the company and said they would send me a challenge to solve. A tech team would review my submission, and if they liked it, they would interview me.

They mentioned the code didn't need to be production quality, but their email said I could take as much time as I wanted and "keep refactoring until you're happy with it." I spent 8-10 hours on the problem and decided to submit it. Frankly, it's endless to keep optimizing it; it's open-ended regarding where to stop.

After asking at least 10 times via email over a span of a month, the HR finally replied, saying they didn't like my code. The review comments made me realize they were indeed looking for production-ready code. In such cases, problems should be small. The company cannot expect me to spend days and weeks on a problem only to get rejected in the end for such an endless question.

Their emailing system is bad. I had to follow up at least 5 times for one reply from HR.

I had a horrible experience interviewing. Though the challenge was impressive, it is unrealistic to expect a working professional to work on their long challenge.

A custom implementation of Message Queues for Amazon SQS, based on the description provided.