[Too]

Agree. While the solution is impressive, the choice of using the type system severely hampers the ways the code can be deployed. Instead of taking dynamic input, the DATA array must now be encoded up-front in an unexpected number-base and run within the tsc compiler. It limits the number of members in the team that can maintain it. Finally, he was lucky there were no further silly requirements like send a PDF report to the CTO if the number is divisible by 201 and it's a Monday. While i also disprove of the interview setup and their bizarre artificial limitations, in the real world shit also happens and you need to react to it, if you decided to prematurely constrain yourself for the sake of scratching your own itch, you could set back progress for weeks, i see this happen all the times with people choosing the wrong tool for the job or reinventing what already exists in the standard library. Long term maintainability and pragmatism is valued higher by the business.

In my books this choice alone wouldn't be cause for rejection, a good interviewer would question it though and depending on the reaction, it could be. Whether or not that happened here isn't clear. They could also have other even better candidates to pick.

[Dylan16807]

There are two things that make it hard to maintain.

One is choice of language, which is supposed to not matter because it's just an interview exercise where you can pick any language.

The other is the contortions around not using numbers.

Anything stemming from those two factors should not be held against the candidate. It definitely shouldn't be labeled as "scratching your own itch".

[remich]

I noticed this in the throwaway comment that the OP made at the end about their prior job disfavoring the use of TS.

I'm not surprised to see that type of sentiment from someone who is (at least self-described) at a more junior level, but still. Often the choice of what language/framework/tool to use on a given codebase or project is dictated or constrained by considerations other than which one is "best" in a technical sense.

Does this suck? Yeah, most of us have strongly held opinions or like to try out new shiny things. But it's a reality of working in this field and coworkers who refuse to learn it can be really hard to work with.