mp_mazes

Goals and Overview

In this MP you will:

• Implement the disjoint sets data structure.
• Create a program to generate random mazes.
• Applying a BFS traversal to a maze structure
• Represent a maze and its solution on a PNG.

Checking Out the Code

All assignments will be distributed via our release repo on github this semester. You will need to have set up your git directory to have our release as a remote repo as described in our git set up

You can merge the assignments as they are released into your personal repo with

git pull --no-edit --no-rebase release main
git push

if you are using multiple machines you may need to use the following to allow them to work correcly.

git pull --no-edit --no-rebase release main --allow-unrelated-histories
git push

The first git command will fetch and merge changes from the main branch on your remote repository named release into your personal. The --no-edit flag automatically generates a commit message for you, and the--no-rebase flag will merge the upstream branch into the current branch. Generally, these two flags shouldn’t be used, but are included for ease of merging assignments into your repo.

The second command will push to origin (your personal), which will allow it to track the new changes from release.

You will need to run these commands for every assignment that is released.

All the files for this mp are in the mp_mazes directory.

Preparing Your Code

This semester for MPs we are using CMake rather than just make. This allows for us to use libraries such as Catch2 that can be installed in your system rather than providing them with each assignment. This change does mean that for each assignment you need to use CMake to build your own custom makefiles. To do this you need to run the following in the base directory of the assignment. Which in this assignment is the mp_mazes directory.

mkdir build
cd build

This first makes a new directory in your assignment directory called build. This is where you will actually build the assignment and then moves to that directory. This is not included in the provided code since we are following industry standard practices and you would normally exclude the build directory from any source control system.

Now you need to actually run CMake as follows.

cmake ..

This runs CMake to initialize the current directory which is the build directory you just made as the location to build the assignment. The one argument to CMake here is .. which referes to the parent of the current directory which in this case is top of the assignment. This directory has the files CMake needs to setup your assignment to be build.

At this point you can in the build directory run make as described to build the various programs for the MP.

You will need to do the above once for each assignment. You will need to run make every time you change source code and want to compile it again.

Assignment Requirements

These are strict requirements that apply to both parts of the MP. Failure to follow these requirements may result in a failing grade on the MP.

• You are recommended to add descriptive comments throughout coding the MP. This will assist you in debugging process.
• You must name all files, public functions, public member variables (if any exist), and executables exactly as we specify in this document.
• Your code must produce the exact output that we specify: nothing more, nothing less. Output includes standard and error output and files such as Images.
• Your code must compile on the EWS machines using clang++. Being able to compile on a different machine is not sufficient.
• Your code must be submitted correctly by the due date and time. Late work is not accepted.
• Your code must not have any memory errors or leaks for full credit.
• Your public function signatures must match ours exactly for full credit. If using different signatures prevents compilation, you will receive a zero. Tests for const-correctness may be performed separately from the other tests (if applicable).

Assignment Description

You will be implementing a Disjoint set data structure and then implementing a random maze generator and solver. The assignment is broken up into the two following parts:

• Part 1 — The DisjointSets data structure
• Part 2 — The SquareMaze random maze generator and solver.

As usual, we recommend implementing, compiling, and testing the functions in Part 1 before starting Part 2. Submission information is provided for each part in the respective sections below.

Part 1: The DisjointSets data structure

The DisjointSets class should be declared and defined in dsets.h and dsets.cpp, respectively. Each DisjointSets object will represent a family of disjoint sets, where each element has an integer index. It should be implemented with the optimizations discussed in lecture, as up-trees stored in a single vector of ints. Specifically, use path compression and union-by-size. Each element of the vector represents a node. (Note that this means that the elements in our universe are indexed starting at 0.) A nonnegative number is the index of the parent of the current node; a negative number in a root node is the negative of the set size.

Note that the default compiler-supplied Big Three will work flawlessly because the only member data is a vector<int> and this vector should initially be empty.

The addelements function

See the Doxygen for this function.

The find function

See the Doxygen for this function.

The setunion function

See the Doxygen for this function.

The size function

See the Doxygen for this function.

Testing Part 1

The following command can be used to compile the DisjointSets test executable:

make testdsets

The following command can be used to run the test executable:

./testdsets

Provided Catch test cases are available as well by running:

make test
./test

Grading Information — Part 1

The following files are used to grade mp_mazes:

• dsets.cpp
• dsets.h

All other files including your testing files will not be used for grading.

Extra Credit Submission

For extra credit, you can submit the code you have implemented and tested for part one of mp_mazes. You must submit your work before the extra credit deadline as listed at the top of this page. See Handing in Your Code for instructions.

Part 2: The SquareMaze random maze generator and solver

The SquareMaze class should be declared and defined in maze.h and maze.cpp, respectively. Each SquareMaze object will represent a randomly-generated square maze and its solution. Note that by “square maze” we mean a maze in which each cell is a square; the maze itself need not be a square. As always, we recommend reading the whole specification before starting.

Videos

• Cycle Prevention / Detection

The makeMaze function

See the Doxygen.

The canTravel function

See the Doxygen.

The setWall function

See the Doxygen.

The solveMaze function

This should be completed using BFS. Do not use DFS since due to the structure of mazes having very long paths it has been known to fail on some test cases running out of memory. Though these are recursive algorithms the solution should not implement them recursively.

See the Doxygen.

The drawMaze function

See the Doxygen.

The drawMazeWithSolution function

See the Doxygen.

Testing Part 2

Square Maze Testing

Since your mazes will be randomly generated, we cannot provide you with any sample images to diff against. However, we have provided you with all four possible 2x2 mazes. If you have your program create and solve a 2x2 maze, the resulting image (with solution) should match one (and only one) of the provided images m0.png, m1.png, m2.png, and m3.png. We strongly suggest that you diff against these to make sure that you have formatted the output image correctly.

We provide some basic code to test the functionality of SquareMaze.

The following command can be used to compile the SquareMaze test executable:

make testsquaremaze

The following command can be used to run the test executable:

./testsquaremaze

You can compare the console output of your program with the expected by comparing it with the file soln_testsquaremaze.out.

Runtime Concerns

You should strive for the best possible implementation. This MP can be implemented so that the given testsquaremaze.cpp runs in less than a quarter of a second on the EWS linux machines. To have a high probability of finishing within the time constraints of the grading script, make sure you can run the given testsquaremaze.cpp in under 3 seconds on an unencumbered machine. You can time mp_mazes by running the command time ./testsquaremaze.

Grading Information — Part 2

• We will use canTravel to reconstruct your randomly generated maze in our own maze class, to check that it’s a tree and to compare your implementation to a correct implementation of this MP. This will require height*width*2 calls to canTravel. Therefore, it is very important that canTravel works, and works quickly (constant time). If it doesn’t work, you will lose a lot of points.
• We will use setWall to replace your maze with our own, for the purpose of testing all of your other functions independently of your createMaze.

The following files are used to grade mp_mazes:

• dsets.cpp
• dsets.h
• maze.cpp
• maze.h

All other files will not be used for grading.