instead of map(val => Number(val)) you can just write map(Number)

"one distinct country" in description is Ukraine

if array were huge you would do it three times too ?

What would you do if there were (a, b, c, d, e, f, g, h....) ?

I think if one of calculated "min" is 0 it would be better to stop iteration because "arr" can be huge

I found it. Thanx

Would you mind to explain what your code is doing ?

you should read about graph theory

you must return NEW instance of Vector but you change input

Why this kata is tagged as "OBJECT-ORIENTED PROGRAMMING" ?

"you are not allowed to use the lru_cache decorator from the functools module for this task."

It would be better if basic tests included not only chars but strings too.