Homework 3 has been updated with the following clarifications.
1. A customer can have more than one active rental. That is, they can show up on day 1 and rent 1 video for 5 nights. They can then show up on day 2 and rent another video for 4 nights. As long as they do not have more than 3 videos rented, they are allowed to have multiple rentals.
2. Returns occur at the beginning of the day before the store opens for business. A video rented for one night is available to customers the very next day; that's because the customer rented the video for one night, watched it, and got it back to the store early the next morning.
3. Your program should be single-threaded; you do not need to handle the case of multiple customers trying to rent videos concurrently.