In this assignment, you will use POSIX mutex locks and semaphores to implement a solution

that coordinates the activities of a TA and students as described below.

A university computer science department has a teaching assistant $($TA$)$ that holds office hours

where they provide help to students with their programming assignments. The TA$$s office is rather

small, and only has room for one desk with a chair and a computer. There are three chairs outside

the office where students may sit and wait if the TA is currently helping another student. If there

are no available chairs in the waiting area, the student leaves and shows up at a later time. When

the TA has finished helping a student, she goes outside to the waiting area to see if there are

waiting students. If so$,$ she takes the next student and begins to help them. If there are no waiting

students, she returns to her chair in he office and takes a nap. If a student shows up and sees the

TA sleeping, the student wakes her up$.$

Using POSIX mutex locks and sempahores, design a solution to coordinate the activities of the

TA and students. A simple solution can use one mutex lock and two semaphores: $($i$)$ the mutex

lock for controlling access to the chairs. You will need to keep track of the number of waiting

students and that variable is a shared variable. $($ii$)$ a counting semaphore for waiting students. $($ii$)$

a binary semaphore for represesnting whether the TA is available or not.

Students and the TA: Using Pthreads, begin by creating N students where each student runs

as a separate thread. In addition, the TA will also run as a separate thread. Student threads will

alternate between programming for a period of time, and then seeking help from the TA$.$ If the TA

is available, they will obtain help or will sit in a hallway while waiting their turn with the TA$.$ If

there are no chairs available, the student will resume programming on their own, and seek help at

a later time. If a student arrives and notices the TA is sleeping, they must notify the TA using the

appropriate semaphore.

If the TA is helping a student, upon finishing they must check if there are waiting students in

the hallway. If so$,$ they must help them as well. They will notify a waiting student by using the

appropriate semaphore. If there are no waiting students, the TA can take a nap.

Programming and Helping: Perhaps the best way of simulating the students programming

and the TA helping a student is for them to sleep for a random period of time using the sleep$()$

function, and displaying a message on what they are doing, e$.$g$.$TA is helping student number

$1..$