Sharing assignments with a potential employer
I don't think you need to worry about school policy or copyright here: you're privately sharing these documents in order to allow somebody to better evaluate you, not attempting to transfer ownership or widely distributing them.  

As such, the question of who owns the code is irrelevant: you are not claiming ownership, you are claiming that the portions you wrote provide evidence of your skills as a programmer.  The company should be expected to treat it as a confidential part of your application process, just like all of the other personal information that you have given them.  If they do not, any possible fault and liability lies with them, not with you.