A friend, who had interviewed with Dropbox previously but received no offer, introduced me to the recruiter via email. The recruiter responded about two weeks later and sent me a HackerRank coding question. I didn't think it would be very difficult, as I've completed HackerRank coding questions for other companies with ease. Oh, how naive I was.

The question was very difficult, at least for me. It was a pattern-matching question that seemed to require coding a lexical analyzer in an hour.

Based on what I've read on Glassdoor, other candidates went straight to HR screening interviews or technical interviews. I believe I was given an exceptionally hard coding challenge so that the recruiter could say they gave me a chance, but they weren't going to bother with me unless I was extremely smart. It was really just a courtesy coding challenge, and they had already decided to reject me. Seeing as how I was recommended by a previously rejected candidate, I suppose I should have seen their veiled rejection coming in the form of a coding challenge.

I'm really disappointed at Dropbox's recruiting practices. I've worked at Microsoft before and interviewed at Google, Facebook, Square, Twitter, Airbnb, Pinterest, etc., and I've never had this sort of treatment.

Question: Given a pattern and a string input, find if the string follows the same pattern and return 0 or 1.

Examples:

1. Pattern: "abba", input: "redblueredblue" should return 1.
2. Pattern: "aaaa", input: "asdasdasdasd" should return 1.
3. Pattern: "aabb", input: "xyzabcxzyabc" should return 0.

I saw someone else had a similar question, but it was much easier, as the other candidate was given spaces between words to help identify individual words for pattern matching.