First round was a 20 minute phone call about my interests, previous experience and expectations from the co-op.

Then you get an email to schedule a technical on-site interview where you get 30 minute interviews with different teams depending on which ones are interested in you; please note that you can get multiple rounds.

Lastly, you get a 30 minute rotation with with a current co-op in which you can ask questions and tour the building.

I implemented a BST lookup and a quick comparison between the recursive and iterative versions.

How can you troubleshoot a slow SQL query and what are some possible optimizations?

Given two strings, check if you can form the second string using characters in the first one.