I applied via a career fair at school.

I was then called in for an on-campus interview.

The person interviewing me didn't focus much on my resume; we jumped right into a whiteboard coding question.

He wasn't the friendliest and seemed condescending.

He treated me like a senior student, even though I was just a freshman, and expected the most efficient code possible for the questions.

Compare two strings and see if they have the same frequency of letters, with maximal efficiency.