same here.. did this same thing with string builder :D..

But don't throw exception with null and str.length() < 2

Omg, it's was so ez.

It's 'length', not 'lenght'! ;)

Yes

Because that method returns another string, it doesn't mutate the string in place. Use spoiler flag next time, please.

You don't want to run the while loop once it has already reached the goal population.

Not true for me. Worked fine with > 7

User should not have to add this in their code

use std::collections::HashSet;

to get it to work.

Needs to be in set up of test suite

Look at the top of the page: 7789 guys passed the Python translation.

The description says to be a senior, you must have a handicap greater than 7. Not 7, but strictly greater. It only took my solution when I allowed handicp to be 7. Need to fix tests or description.

sadly, yes, but at least I've gained experience in making a kata

Unfortunately, it is pretty much a duplicate of this one https://www.codewars.com/kata/age-range-compatibility-equation

You'll need something more original, or need more checking for duplicates to avoid in future...