Just my luck, this was found immediately in the CI, right when I
uploaded the project thinking I was done.
Thankfully the fix is easy and (in hindsight) quite obvious.
From what I could find, the rules of the assignment seem to be:
1. Restrict oneself to at most *one* O(log(N)) call, and otherwise use
constant time operations on the map.
2. Don't use more operations than strictly necessary on `K` and `V`.
3. Prefer simplicity to performance.
I think my solution would fare well under those constraints.
Bruno BELANYI