Because the problem asked for it. We are to define methods on Object that already exist as Array methods. You can do it longhand or via this concise shortcut. End result is the same.

Ran the maths, checks out you're valid. Nice one.

Please, do the math / consider the logic.

Please, take a look at the problem description.

it does not actually have to include your points

it does not actually have to include your points

It doesn't include your points

I liked that :)

You forgot to count your points, I'm surprised this passed

Man, I need to start remebering that min and max exist.

What on Earth
Nice one.

...why...?

can't be changed

The description specifically states that the string will consist only of letters a-z. So in practive your solution would be best, but in the context of this kata, the OP's is fine.