Skeleton Code

Skeleton files for the problems below can be downloaded here. There is a subfolder for each of the two problems below.

Midterm

1. (14 pts) Inheritance And Class Hierarchies

Billy Bruin wrote a class in inh.cpp that models a college course and its assignment from numeric grades to corresponding letter grades. Each course object must store the course name (e.g. "CS104") and a map of student names and their numberic grades (map<string,double>). The map of grades can be set by calling setGrades(). The objective of this class is to output letter grades via a function outputGrades(). However, to determine letter grades, there are 3 types of classes:

• Pass/No Pass. In this type of class, a threshold value (e.g. 70) can be supplied and any numberic grade greater than or equal to the threshold will be considered passing (output P) and anything below the threshold is not passing (output NP). The threshold can be set via setPassThreshold().

• Straight Scale. In this type of class, letter grades are assigned according to a fixed scale where (A >= 90, B >= 80, C >= 70, D >= 60, F >= 0). The scale will be stored internally as a map<string,double> where the key is the letter grade and the value is the lower-bound on the score needed to get that grade (i.e. A,90.0). outputGrades() should just output the key (string) that is provided in the map that correponds to the appropriate lower-bound associated with that key.

• Custom Scale. In this type of class, letter grades are assigned according to a custom scale that the user can supply in the form of a map<string,double> where the key is the letter grade and the value is the lower-bound on the score needed to get that grade (i.e. A,85.5, B,72.0, C,65.75, D,50.0, F,0). It is up to the user to call setScale() for this type of course.

Currently, the code provided in inh.cpp implements these 3 course types in a single Course class. Your task is to alter the code to introduce a class hierarchy (base and derived classes with appropriate hierarchy), such that:

• Code and data that pertains only to a particular type of course (Pass/NoPass, Straight Scale, Custom Scale) does not exist in the classes corresponding to other types.

• Reduce duplication of code and/or data members (i.e. as much reuse as possible) between base and derived classes, subject to the previous goal above about code/data specific to one course only being in that (those) classes.

• Allow for different types of courses to be stored together in a vector/array, etc. and specifically to allow for iteration over all the course objects to output their grades. Creation of the objects is allowed to be performed on specific course types.

• Define appropriate (pure) virtual functions as necessary that correspond to good coding practices defined in class.

• The main program can be updated in the indicated sections (where you create the 3 courses)

• Your updated code produces the same output of the original code.

• You may define and implement the base and derived classes all in inh.cpp.

We will score your submission based on its adherence to the above bullets and the level to which it meets those requirements.

2. (18 pts) ADTs and STL

Overview

In this problem, you will complete a class to model a Piazza-like system of “posts”, some of which can be “pinned” and which can be searched quickly to see if they contain a particular term/word.

Classes and Your Task

We have provided a Post object that can be used to store the text of the post and, potentially other information of your choice, and act as a single item in a linked list.

Furthermore, we have implemented a rudimentary PostList that provides code to implement a simple linked list of Posts. You must use this class in the implementation of the Piazza class below.

Your task is to implement the Piazza class. This class inherits from PostList (you should determine the kind of inheritance). This class implements the notion of a pinned post which is a subset of the overall list of posts. In addition, the user can query how many posts contain a particular word/term. This query should be performed efficiently (see the runtime requirements in the header file.)

Complete the Piazza class (in piazza.h and piazza.cpp) by choosing the kind of inheritance, adding data members, specifying any inheritance relationship, implementing the public functions according to the requirements and run-time limits provided in the comments in the header file, and adding any private helper functions you wish. You may add data members to the Post struct as you deem useful.

Public operations of the Post class include:

• Adding a Post (via the provided input string).
• Determining how many posts contain a given (single)word. To make your life easier, you may perform case-sensitive searches so that no extra processing is needed.
• Retrieving the i-th most recent overall post (either pinned or non-pinned).
• Retrieving the i-th most recent pinned post.

You do not have to support removal/deletion of posts.

You may use std::vector, std::set, and std::map. You may not use std::list. If you want a linked-list you will need to write code to manage it yourelf. (That doesn’t mean you should write a list class but can just embed code to manage a linked list…and you may define new structs).

Again, the specifics of each post are listed in the documentation/comments in the header file. You must meet these requirements including the run-time requirements listed.

Running and Testing your Code

We have provided a Makefile with a make test rule that will compile your code and run a few unit tests define in piazza-tests.cpp. You are welcome to add to this file as you see fit.