PART A $-$ LinkedLists $(55$ marks$)$

When a student wishes to register for a course, they are placed on a waitlist if the class is already full.

Students can register from the waitlist when a spot become available and if they have permission. In our

simplified simulation of a waitlist, the system randomly performs one of four operations and updates the

waitlist accordingly. For simplicity, we assume that:

$-$ only one operation can be performed in a day;

$-$ a waitlisted student has a maximum of two days to complete their registration once they are

permitted to register. If not registered after two days, the student becomes the last person on

the list, in order to give other students a chance;

$-$ only one student $($first person on the list$)$ can be granted permission to register at any point.

$-$ A waitlisted student is a student with a waitlist status $($Waitlisted or PermittedToRegister$)$ and

may have some number of days left to complete registration if they have been permitted to

register.

The details of each operation and the rules applying are provided below: