Dang. I always forget about using the spread operator to make a shallow copy of an array. Good job.

Thank you for your fast reply :)
I'm still learning about how to recognize and subsequently reduce complexity.

see message above.

Thank you =D

Best solution I seen, good work!

Based

Very true!

sort mutates the original array so spreading here creates a new reference and avoids mutation. Not necessary in the exercise, true, but still worth using in a real application

[...arr] no need for this spread lol. arr is already an array

agree ;)

@JChampt in my opinion, sorting is a bottleneck in your solution

Clever. I didn't think about using hash table for keeping both indexes and watching for a duplicate. I used a Set for the latter.

Good answer, but the formatting needs some work. The variable names should be descriptive, and the return value should get its own line.

I like the clever use of the or statement to catch the out of bounds indexing of the array. I made a slice instead, but I suspect your solution is faster. Nice one!