Nice and readable. Well done.

e is a math constant, Euler's number (2,72)

Cool solution!

What would you name it instead? I came up with the same solution, but used "item" instead of "e." (Also - how would you use "e" as a number in math? - You got me all curious now!)

I solved the problem in the same way, but
if the array has a value of 0 , the function will return -0

In Math "e" is a number, not sure if is a good idea to name it with "e", but your solution is great!

The array of IDs may have duplicates but don't need to find or remove them.

so, to make the IDs unique without removing or finding them, I passed the arrays to the set

I took this statement to mean that we should find a solution that does not require the removal (even the temporary removal) of duplicates:

there may be duplicate IDs, but you don't have to find or remove them!