I tested it out. Version without set() is much much slower than any other solution pasted here.

This should not be best practices.

Time of execution for long text of this version: 0.27908778190612793
time of exection for long text where you iterate over set: 0.0005300045013427734

@noweare

yes, it is one of the greatest features of this site

CPU go brrrrrrrr

great job.

This solution is very inefficient, being O(n^2), when it easily could have been made O(n)
Not every one-liner is clever or best practice.

@sztssp

Maybe perhaps it won't be for a larger data! (like an entire paragraph)!!! Would be a good experiment to test it!

Getting all of them can be very expensive for large arrays with small n.

Its a good answer

Could anyone explain why this is O(n2) instead of O(n) please?

Me too, i think i learn more by others solutions

It doesn't modify the arrays, but creates a new array.