So what went wrong. 1) Technical interviewer probably doesn’t know Java at the level expected to interview candidates. Why? Because when I asked him what kind of data structure I may expect as an input for this example of data: [["grapes", 1],["apples", 0],["peaches", 1]] - he replied arrays only. That was a first call to me actually - Java doesn’t allow for arrays to mixed types, but that was exactly what he was requested me to do. However my explanation was not enough for the first time and then I asked him then the second question - what should be the length of the array representing a basket? It’s nothing wrong with an answer like he did - “More than 3” in case you’re using some other language rather than Java (and some others), because in Java the array length is a deterministic value and must be predefined during declaration! I had to explain him that it is not possible in Java to create an array with indeterministic length - we have to use List interface instead. Only after that, interviewer recommended me to use List (!) interface :) I understand at that point he might be a professional in development well, may be using other languages, but basics... So I had to explain him that we must (in case he doesn’t want to use abstraction in an example I described above) use Map interface if he insist to keep that structure: ["grapes", 1] Eventually he was convinced and I started the implementation :) 2. Technical interviewer either didn’t correctly understand the task or didn’t correctly describe it. I'd like to describe it here, but Glassdor doesn't allow me to type more than 5000 symbols :)