Voleon Software Developer interview questions

I was asked to complete a coding challenge on hackerrank. There were some technical difficulties but I ended up submitting it. While I passed all the test cases on the hackerrank website, they felt code wasn't easy to understand and that was the primary reason they didn't want to move forward. Personally, I didn't think it was difficult to understand but I have heard that feedback before and I don't have a significant amount of software experience, so I just took the feedback in stride. The challenge is not difficult; however, the directions are difficult to understand and there's some ambiguity/vagueness in the directions which make it hard to understand what to do in certain cases. I was pretty convinced that one of the test cases was based on a different interpretation of the directions than what was stated. I feel that their challenge needs to be significantly re-worked so that it's clearer.

Initial phone call, hour-long technical phone interview, online coding challenge (larger and more complex than challenges from other companies - I used almost an entire day for it), and finally an onsite.