Homework 3 — Election

Homework 3 — Election

(125 points)
This is an individual coding assignment. You may have one design buddy, as described below. Having a design
buddy is *highly* recommended. You will be attending interview grading for this assignment the week following
submission.
Objectives:
- Develop familiarity with the concept of “static”
- Implement and use the Singleton design pattern
- Design and implement a multi-object program, dealing with the intricacies of objects communicating
with one another
Credit:
- hw3_design.pdf (deliverable 1)
- Makefile, ElectoralMap.[h,cpp], District.[h, cpp], main.cpp (deliverable 2)
- Makefile, all header and implementation files, main.cpp (deliverable 3)
- output.txt
Instructions:
You will write a program that simulates elections. You will use inheritance to implement two kinds of elections: a
direct election in which constituents vote directly for candidates and the candidate with the most votes wins
(regardless of whether or not that candidate has received a majority of votes), and a representative election in
which all representatives from a district vote for the candidate who received the most votes (again, not
necessarily a majority) in their district.
Part 1 (Design Document & getting started):
Design Document (deliverable 1):
You may have one design buddy for this assignment. You and your design buddy should figure out which
classes are in charge of what (see class description table later in the assignment), how they will communicate
(what methods they will have), and what data they will control (what fields will they have). You and your design
buddy cannot write code together, but you may discuss what each method should be doing in general.
If you have a design buddy (recommended), you should indicate this in comments at the top of your main.cpp
file as well as in your design document. Your design document, whether created with a buddy or not, is worth
10 points.
Your design document should be similar to the document that you produced for PE 6 when diagramming the
provided code. You do not need to follow a formal diagramming language, but your diagram needs to be legible
and communicate the information described above.
It must include:
CSCI 3010 — Fall 2021 — Homework 3 1
a) the interfaces that your classes will have (what methods will they have, what methods will they
call/use?)
b) the data members (fields/attribute) that your classes will have
c) pseudocode for your main function
Program Flow:
1) First, you should create an Election or a RepresentativeElection based on whether the user chooses
"direct" or "representative".
2) Next, you should register Candidates for that election.
3) Then, Candidates are allowed to campaign as much as they want. When all Candidates are done
campaigning, this step is over.
4) Finally, the Election calls for votes from the Districts.
5) These votes are tallied (differently for Elections vs. RepresentativeElections) and a winner is
announced.
6) Return to step 1, using a new Election, but maintaining the same ElectoralMap.
Next, a note on randomness:
You only want to seed your random number generator once each time your program runs. You should not seed
your random number inside of a loop, for instance.
Campaigning and converting constituents:
If a Candidate chooses to campaign in a given District, they can have 1 of the following 4 outcomes:
1) A constituent is converted from Party::None to the Party of the Candidate.
2) A constituent is converted from Party::None to the Party of the Candidate and a constituent is
converted from the majority Party that is not the Candidate’s Party to the Party of the Candidate.
3) A constituent is converted from the majority Party that is not the Candidate’s Party to the Party of the
Candidate.
4) No one is converted.
To determine which of these situations occurs, the probability of the candidate is calculated according to the
following formula:
𝑃
𝑠𝑢𝑐𝑐𝑒𝑠𝑠 = 𝑚𝑖𝑛(100,
(𝑐𝑜𝑛𝑠𝑡𝑖𝑡𝑢𝑒𝑛𝑡𝑠 𝑓𝑟𝑜𝑚 𝑡ℎ𝑒 𝐶𝑎𝑛𝑑𝑖𝑑𝑎𝑡𝑒'𝑠 𝑃𝑎𝑟𝑡𝑦 + 1) * 2
( 𝑐𝑜𝑛𝑠𝑡𝑖𝑡𝑢𝑒𝑛𝑡𝑠 𝑖𝑛 𝑜𝑡ℎ𝑒𝑟 𝑃𝑎𝑟𝑡𝑖𝑒𝑠 𝑖𝑛 𝑡ℎ𝑖𝑠 𝐷𝑖𝑠𝑡𝑟𝑖𝑐𝑡, 𝑒𝑥𝑐𝑙𝑢𝑑𝑖𝑛𝑔 𝑃𝑎𝑟𝑡𝑦::𝑁𝑜𝑛𝑒 ) *
(𝑐𝑜𝑛𝑠𝑡𝑖𝑡𝑢𝑒𝑛𝑡𝑠 𝑓𝑟𝑜𝑚 𝑡ℎ𝑒 𝐶𝑎𝑛𝑑𝑖𝑑𝑎𝑡𝑒'𝑠 𝑃𝑎𝑟𝑡𝑦 + 1) * 2
( 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑡ℎ𝑖𝑠 𝐷𝑖𝑠𝑡𝑟𝑖𝑐𝑡 ))
𝑃
𝑒𝑥𝑡𝑟𝑎 𝑠𝑢𝑐𝑐𝑒𝑠𝑠 = 𝑃
𝑠𝑢𝑐𝑐𝑒𝑠𝑠
* 0. 1
𝑃 is the probability of converting a constituent affiliated with Party::None. is the probability of
𝑠𝑢𝑐𝑐𝑒𝑠𝑠
𝑃
𝑒𝑥𝑡𝑟𝑎 𝑠𝑢𝑐𝑐𝑒𝑠𝑠
converting a constituent from the majority Party that is not the campaigning Candidate’s and is not Party::None
to the Candidate’s Party. You only need to generate 1 random number. If it fulfills both these categories then
two people should be converted. If there are no constituents with the needed affiliation, simply do not convert
anyone from that affiliation.
CSCI 3010 — Fall 2021 — Homework 3 2
Scenario 1 occurs if 𝑃 and not . Scenario 2 occurs if and . Scenario 3
𝑠𝑢𝑐𝑐𝑒𝑠𝑠
𝑃
𝑒𝑥𝑡𝑟𝑎 𝑠𝑢𝑐𝑐𝑒𝑠𝑠
𝑃
𝑠𝑢𝑐𝑐𝑒𝑠𝑠
𝑃
𝑒𝑥𝑡𝑟𝑎 𝑠𝑢𝑐𝑐𝑒𝑠𝑠
occurs if 𝑃 and but there are no constituents associated with Party::None. Scenario 4 occurs if
𝑠𝑢𝑐𝑐𝑒𝑠𝑠
𝑃
𝑒𝑥𝑡𝑟𝑎 𝑠𝑢𝑐𝑐𝑒𝑠𝑠
either not 𝑃 or if there are no constituents with the needed affiliation.
𝑠𝑢𝑐𝑐𝑒𝑠𝑠
Creating your ElectoralMap:
Your ElectoralMap may have any number of Districts. This number should be hard coded as a static const int in
your ElectoralMap. Your program should work if you change this number for any number of Districts. We
recommend starting with 1 or 2 for debugging purposes.
Districts are generated randomly according to the following rules:
- Each Party begins with a random number of constituents between 0 and 9, including Party::None.
Generate a random number for each Party.
- Each District is between 5 and 29 square miles, again chosen randomly.
- Each District should be given an id, generated by the ElectoralMap.
When you go from one Election to a new Election, your ElectoralMap must not change. You should generate it
once and only once. Your ElectoralMap must implement the Singleton design pattern.
Voting:
Constituents vote as follows:
- A constituent aligned with a Party votes for a Candidate aligned with their party 100% of the time if one
exists.
- if multiple Candidates are aligned with this Party, a random one of these options is chosen.
- If the constituent is aligned with Party::None, they vote for the Party that the most constituents in their
District is aligned with 100% of the time.
- If there are multiple Candidates from this Party, a random one is chosen.
- If there are no Candidates aligned with the majority Party, they randomly pick a Candidate.
- If there is no one aligned with a constituent's party and the constituent is not aligned with Party::None,
they vote as if they were aligned with Party::None.
- In all cases, if there are multiple candidates from the same Party or multiple parties with the same
number of constituents, a random choice is made.
- In all cases, constituents always cast a vote.
District votes:
For the RepresentativeElection, there are a total of 5 * the number of Districts votes to be allocated. The
number of votes for a given District is calculated according to the formula:
𝑉𝑜𝑡𝑒𝑠
𝐷𝑖𝑠𝑡𝑟𝑖𝑐𝑡 = 𝑓𝑙𝑜𝑜𝑟(
# 𝑜𝑓 𝑐𝑜𝑛𝑠𝑡𝑖𝑡𝑢𝑒𝑛𝑡𝑠 𝑖𝑛 𝑡ℎ𝑖𝑠 𝐷𝑖𝑠𝑡𝑟𝑖𝑐𝑡 * 1.0
( # 𝑜𝑓 𝑐𝑜𝑛𝑠𝑡𝑖𝑡𝑢𝑒𝑛𝑡𝑠 𝑖𝑛 𝑎𝑙𝑙 𝐷𝑖𝑠𝑡𝑟𝑖𝑐𝑡𝑠 ) * 𝑡𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑑𝑖𝑠𝑡𝑟𝑖𝑐𝑡 𝑣𝑜𝑡𝑒𝑠)
If District A has 7 constituents and District B has 5 constituents, District A would end up with 5 votes and
District B would end up with 4 votes. Notice that the number of total district votes can be less, but never greater
than, the number of total district votes to be allocated.
Name Type Purpose
TextUI class Similar to the TextUI from PE 6, this class should
CSCI 3010 — Fall 2021 — Homework 3 3
facilitate the prompting of the user for various kinds of
information, the routing of that information to the
appropriate objects and the display of program data to
the user.
Party enum class Represents each political party. You may have as many
parties as you wish, but you must include
Party::None and at least two others. Make sure to
design your program so that it could support a variable
number of parties!
Candidate struct or class Candidates have names, party affiliations, and ids.
Candidates cannot be affiliated with Party::None.
Candidates should have ascending ids according to the
order in which they are registered.
Election class The general manager of elections. Registers
candidates, directs them to districts to go campaigning,
calls for the actual votes, and reports the winner after
tallying the score.
At the beginning of an election, a new Election object
should be used (as opposed to having some sort of
Reset method)
RepresentativeElection class (inherits Election) A derived class of Election. Rather than constituents
voting directly for candidates, the candidate that wins a
majority in each district gets all of that District’s votes
(similar to with the American electoral college)
District class Represents a building block of the ElectoralMap.
Districts keep track of their constituents by counting how
many constituents are affiliated with each Party. They
also handle when constituents change from one party to
another. Throughout the course of the program running,
the number of total constituents in each District should
not change.
Districts also have a size in square miles, which affects
how easy it is for candidates to campaign there.
ElectoralMap class (singleton) Keeps track of Districts, manages the logistics of letting
Candidates campaign in Districts, and handles the logic
for determining how many votes each District has in a
RepresentativeElection.
Handles the logic for communicating the votes from
each District to the Election.
We recommend using a static field to assign ids to each
District when they are created so that you can access
them with maps from id to district.
Output:
Output files are on Canvas. You have complete creative freedom in how you design your UI, but it must include
the functionality provided in our output files.
CSCI 3010 — Fall 2021 — Homework 3 4
Getting Started (deliverable 2):
Note: You may find incorporating std::map into your program very helpful.
1. Write the code for a class ElectoralMap that implements the singleton design pattern. When instantiated, this
ElectoralMap should assign unique ids to 4 different Districts and store them in a std::map with int id mapping
to District. You may want to use a static field in the District class to help with generating sequential unique ids.
1. Your District should be a regular class.
2. You should override the operator<< for both the ElectoralMap and the District.
3. You should use a static const int field in your ElectoralMap to designate the number of Districts,
similar to what we saw in the Earth examples for number of continents.
4. Each District should start with a random area between 5 and 29 square miles.
5. You should implement a get_district(int id) method in ElectoralMap that lets you access Districts by
id.
6. You do not need to implement any other methods. (Though you will want to for your complete
homework!)
7. Test your code when you change your number of districts to a number other than 4.
2. Write a main.cpp concurrently with step 1 and include adequate code to test your ElectoralMap and District
classes.
Part 2 (deliverable 3):
Implement the rest of your program
Comments and style (15 points):
Your files and functions should have comments. We should know how to run your program and how to use
your functions from your comments.
Your variables should have meaningful names. Your code should be easily readable. If you have complex
sections of code, you should use inline comments to clarify.
You should follow the conventions set out in our Concise Style Guide, posted on the course github
Simplified Rubric (meant to give you an idea of how points are distributed and general requirements,
does not show all details)
Part 1 design document (10 points)
Must have plans for the structure, methods, and
fields of the following classes:
-TextUI
- Election
- RepresentativeElection
- ElectoralMap
- District
Must also have pseudocode for your main
function
code implementation (10 points)
- compiles
- appropriate ElectoralMap implementation
- appropriate District implementation
- appropriate main function
20
Party 3
CSCI 3010 — Fall 2021 — Homework 3 5
Candidate - Candidates are assigned ascending ids in the
order in which they are registered
7
Election - no candidates from a previous election are
automatically registered
- can register a candidate for the election.
Including the ability to register multiple candidates
affiliated with the same party for the election.
- correctly reports the winner, counting each
constituent vote equally
- new Election object used at the beginning of
every election
15
RepresentativeElection - Must inherit Election
- must override at least 1 method to conduct the
representative election (dynamic dispatch)
10
District - initialized appropriately
- correctly converts constituents
5 (this is for the logic beyond the
points for getting started)
ElectoralMap - correct logic for determining district votes in a
representative election
- ElectoralMap remains the same from election to
election
10 (this is for the logic beyond the
points for getting started)
Voting - this is for the voting logic, no matter which class
it is in
10
Other Functionality - can register candidates
- can go campaigning
- vote can happen
- elections finish with winners
- can start another election at the end of one
election
30
Style & comments - follows style guidelines
- variables have meaningful names
- implementations are in appropriate locations
- does not have redundant code/unnecessary
conditional branches
(continued)
- file comments
- function comments
- inline comments for complex code
15
CSCI 3010 — Fall 2021 — Homework 3 6