this seems very O(n) to me. I think we should be doing this in O(logn)

Clever, but you mutated the list.

The char datatype can be treated as its unicode equivalent without typecasting or converting. So it's is evaluating the chars based on their unicode equivalents. If you're not familiar with Unicode you definetly need to research it.

Wait im confused, this probably a dumb question but where do you access the alphabet in this?

but you are not meeting the requirements

As many top 'coding craftsman' already said, when your variable needs an explaining comment you did something wrong

I can't believe people upvoted this solution as the Best Practice and Clever... IT MUTATES THE ORIGINAL LIST!
Someone should add such check in Tests.

In this case, I would say that descriptive comments would be preferable to well-named auxiliary variables.

I don't think returning out of a loop is a best practice, but perhaps I'm old-fashioned?

don't change original list.

Yes indeed - there is a H U G E paragraph named EXCEPTIONS - i havn't checked that earlier on - thanks pal.

The exceptions are generated from the Aggregate function.

This link defines the function and there is a section describing the exceptions: https://msdn.microsoft.com/en-us/library/bb548651(v=vs.110).aspx

how come it works without argument exceptions which were a part of this kata?

This implementation contains a bug: it changes the original list.