Sliding Puzzle Game
Assignment 1
Semester 1, 2021
CSSE1001/CSSE7030
Due date: 20:00 (AEST), 26 March, 2021
1 Introduction
In this assignment, you will implement a text-based version of the popular sliding puzzle game.1 It is
recommended that you try an online version of the game to familiarise yourself with the concepts and
gameplay.2
2 Getting Started
To start, download a1.zip from Blackboard and extract the contents. The a1.zip archive contains all the
necessary files to start this assignment. Some support code has been included to assist with implementing
the program.
Within the a1.zip archive you will find the following:
• a1.py: You are required to implement your assignment solution entirely within this file. It includes
some initial code to help you get started on the assignment. This is the only file that you will submit
for this assignment, do not make changes to any other files.
• a1 support.py: This file contains code that you must use to assist you in implementing your assignment.
The content of this file is described in Section 6.1.
• words.txt: This file contains a number of common English words.3 The file is used to generate new
sliding puzzles, however, you are not to generate puzzles from this file yourself, instead, you will use
functions available in a1 support.py to read the file contents.
3 Terminology
In the context of this assignment:
• Sliding puzzle is a puzzle consisting of a square-shaped grid.
• The grid is evenly divided into tiles, with the same number of tiles in each row and column.
• Tile is a single cell in the grid containing a single letter, or is a blank tile.
• Blank tile represents an empty space in the physical puzzle on which this assignment is based.
• Puzzle is a grid in which every tile contains a single letter, except for a single tile that is blank.
• Solution is a grid which is filled so that every tile contains a single letter.
• The player’s goal is to solve the puzzle by sliding the non-blank tiles so that the grid corresponds to
the solution, with the blank tile at the bottom right corner.
1https://en.wikipedia.org/wiki/Sliding_puzzle
2https://www.helpfulgames.com/subjects/brain-training/sliding-puzzle.html
3https://github.com/first20hours/google-10000-english
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An example of the sliding puzzle games is shown in the image below.
a b c
d e f
g h i
Solution
h g c
d b e
f a
Shuffled Puzzle
a b c
d e f
g h
Solved Puzzle
a
b e
2x2 Puzzle
4 Game Stages
4.1 Setup
At the beginning of the game, the player is asked to choose a difficulty. Difficulty is an integer which is the
number of rows and columns of the puzzle. This determines the size of words used in the puzzle, where each
word fits into one row. You may assume the difficulty (size of the puzzle) given by the player is an integer
between two and fourteen.
After the difficulty is specified, a solution is generated from the words provided in a word file. A shuffled
puzzle is then generated by shuffling the tiles in the solution and replacing the tile at the bottom right
corner with an empty tile.
4.2 Solving the Puzzle
The player tries to solve the puzzle by sliding the tiles to reach their goal. At each turn, the solution and
current state of the game are displayed. The player is then prompted to enter an action. The action can be
one of the following:
Input Description
"H" Display a help message.
"GU" Stop playing the current game.
"U" or "D" or "L" or
"R"
Move the empty tile in the up/down/left/right
direction, respectively.
The prompt will repeat until the player either wins the game, or gives up by entering the "GU" action.
4.3 End of Game
At the end of a game, the player is prompted to choose if they want to start a new game or to stop the
program.
Input Description
"Y" or "y" or "" Start a new game.
Anything else Close the program
If they choose to start a new game, they need to set a new difficulty. A new solution and puzzle are
generated, and the new game is started.
5 Conventions
This assignment follows the conventions specified below:
1. solution: A solution is stored in a string. This string contains all letters in the grid from left to right
and then top to bottom, without any special characters and/or new lines. For example, the solution,
"dogcatpig", represents the grid below:
2
d o g
c a t
p i g
2. puzzle: The puzzle is a string that is a copy of the solution, except for the last character. All the
characters in the puzzle are shuffled at the start of the game. A space character (i.e. " ") is added to
the end of the puzzle to represent the blank tile. For example, after several moves the puzzle, "fhg
bcade", is represented by the grid below:
f h g
b c
a d e
To implement the logic of sliding a tile, you need to swap the position of the character in the string
that is being slid with the position of the space character. Your logic needs to ensure that you only
perform the swap if the character and the space are adjacent to each other in the grid.
3. direction: A direction can either be "U" or "D" or "L" or "R", which correspond to up/down/left/right.
6 Implementation
The following functions must be implemented in a1.py. You may implement additional functions, if you
think they will help with your logic or make your code easier to understand. These functions have been
listed in order of increasing difficulty.
check win(puzzle: str, solution: str) -> bool
Returns True if the game is won, given the puzzle and the solution, and False otherwise. Examples of
calling check win:
>>> check_win("abcdefgh ", "abcdefghi")
True
>>> check_win("dabecghf ", "abcdefghi")
False
swap position(puzzle: str, from index: int, to index: int) -> str
Swaps the positions of the characters at from index and to index in the puzzle and returns the updated
puzzle. Examples of calling swap position:
>>> swap_position("care", 0, 2)
’race’
>>> swap_position("does", 3, 2)
’dose’
move(puzzle: str, direction: str) -> Optional[str]
Moves the empty tile in the given direction and returns the updated puzzle. If the move cannot be
made (i.e. moving in the given direction results in the empty tile being outside the grid), it returns None.
Examples of calling move:
>>> move("abcdefgh ", "U")
’abcde ghf’
>>> move("abcdefgh ", "R")
>>>
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The first line of code in the examples above moves the empty tile from the bottom corner up by one tile. It
corresponds to the following graphical demonstration.
The second line of code returns nothing. This is because the empty tile is in the bottom right corner and
cannot be moved to the right.
print grid(puzzle: str) -> None
Displays the puzzle in a user-friendly format. Examples of calling print grid:
>>> print_grid("nevagonagiveu up")
+---+---+---+---+
| n | e | v | a |
+---+---+---+---+
| g | o | n | a |
+---+---+---+---+
| g | i | v | e |
+---+---+---+---+
| u | | u | p |
+---+---+---+---+
>>> print_grid("nevergonnalet udooooowwwn")
+---+---+---+---+---+
| n | e | v | e | r |
+---+---+---+---+---+
| g | o | n | n | a |
+---+---+---+---+---+
| l | e | t | | u |
+---+---+---+---+---+
| d | o | o | o | o |
+---+---+---+---+---+
| o | w | w | w | n |
+---+---+---+---+---+
main() -> None
Handles the main user interaction in the game, as specified in Section 4.2. You need to replace the print
statement with the main logic of your program.
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6.1 Support Code
The file a1.py includes an implementation of the shuffle puzzle function. You should not modify this
function. You must call this function once and only once per game to create a shuffled puzzle.
shuffle puzzle(solution: str) -> str
Generates a solvable sliding game given the solution.
This function calls swap position, which is specified above. You must implement swap position before
you can successfully call shuffle puzzle.
You must use the code provided in a1 support.py to implement your assignment. Do not make changes
to a1 support.py as it could cause unexpected errors. In this file you will find some predefined named
constants and functions. You are expected to use the provided named constants in your implementation of
the game. Of the three functions, you only need to call:
get game solution(file name: str, grid size: int) -> str
This function returns a string, which is the solution to the puzzle. The first parameter is the name of the
file from which words are to be loaded. The second parameter is the size of the grid.
7 Example Gameplay
Welcome to the big brain sliding puzzle game.
This game is based on the real life sliding puzzle: https://en.wikipedia.org/wiki/Sliding_puzzle
Try the game online here: https://www.helpfulgames.com/subjects/brain-training/sliding-puzzle.html
Choose your difficulty. The larger the puzzle, the harder it is to solve.
How big do you want the puzzle to be? 2
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| c | f |
+---+---+
| a | |
+---+---+
Please input a direction (enter "H" for instructions): R
'R' is not a possible move here. Please try again.
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| c | f |
+---+---+
| a | |
+---+---+
Please input a direction (enter "H" for instructions): C
That’s not a valid input, try again.
5
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| c | f |
+---+---+
| a | |
+---+---+
Please input a direction (enter "H" for instructions): H
Options:
H: Display this help message
GU: Stop the current game
[U|D|L|R]: Move the empty cell in the up/down/left/right direction,
respectively.
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| c | f |
+---+---+
| a | |
+---+---+
Please input a direction (enter "H" for instructions): U
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| c | |
+---+---+
| a | f |
+---+---+
6
Please input a direction (enter "H" for instructions): L
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| | c |
+---+---+
| a | f |
+---+---+
Please input a direction (enter "H" for instructions): D
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| a | c |
+---+---+
| | f |
+---+---+
Please input a direction (enter "H" for instructions): R
Solution:
+---+---+
| a | c |
+---+---+
| f | c |
+---+---+
Current position:
+---+---+
| a | c |
+---+---+
| f | |
+---+---+
Congratulations, you’ve won the game. Here’s your candy:
___ .-""-. ___
\ "-. / \ .-" /
> -=.\/ \/.=- <
> -=’\ /\’=- <
/__.-’ \ / ’-.__\
’-..-’
Do you want to play again? [Y/n] y
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Choose your difficulty. The larger the puzzle, the harder it is to solve.
How big do you want the puzzle to be? 3
Solution:
+---+---+---+
| r | o | d |
+---+---+---+
| s | e | o |
+---+---+---+
| p | a | r |
+---+---+---+
Current position:
+---+---+---+
| a | r | s |
+---+---+---+
| p | o | d |
+---+---+---+
| o | e | |
+---+---+---+
Please input a direction (enter "H" for instructions): U
Solution:
+---+---+---+
| r | o | d |
+---+---+---+
| s | e | o |
+---+---+---+
| p | a | r |
+---+---+---+
Current position:
+---+---+---+
| a | r | s |
+---+---+---+
| p | o | |
+---+---+---+
| o | e | d |
+---+---+---+
Please input a direction (enter "H" for instructions): D
Solution:
+---+---+---+
| r | o | d |
+---+---+---+
| s | e | o |
+---+---+---+
| p | a | r |
+---+---+---+
Current position:
+---+---+---+
| a | r | s |
+---+---+---+
| p | o | d |
+---+---+---+
| o | e | |
+---+---+---+
Please input a direction (enter "H" for instructions): GU
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Aww, too bad. Better luck next time.
Do you want to play again? [Y/n] n
Bye.
8 Assessment and Marking Criteria
This assignment assesses course learning objectives:
1. apply program constructs such as variables, selection, iteration and sub-routines,
3. read and analyse code written by others,
5. read and analyse a design and be able to translate the design into a working program, and
6. apply techniques for testing and debugging.
8.1 Functionality
Your program’s functionality will be marked out of a total of 6 marks. Your assignment will be put through
a series of tests and your functionality mark will be proportional to the number of tests you pass. If, say,
there are 50 functionality tests and you pass 40 of them, then your functionality mark will be 4050 × 6. You
will be given a subset of the functionality tests before the due date for the assignment.
You need to perform your own testing of your program to make sure that it meets all specifications given
in the assignment. Only relying on the provided tests is likely to result in your program failing in some
cases and you losing some functionality marks. Note: Functionality tests are automated, so string outputs
need to match exactly what is expected.
Your program must run in the Python interpreter (the IDLE environment). Partial solutions will be marked
but if there are errors in your code that cause the interpreter to fail to execute your program, you will get
zero for functionality marks. If there is a part of your code that causes the interpreter to fail, comment out
the code so that the remainder can run. Your program must run using the Python 3.9 interpreter. If it
runs in another environment (e.g. Python 3.8 or PyCharm) but not in the Python 3.9 interpreter, you will
get zero for the functionality mark.
8.2 Code Style
The style of your assignment will be assessed by a tutor. Style will be marked according to the style rubric
provided with the assignment. The style mark will be out of 4.
The key consideration in marking your code style is whether the code is easy to understand. There are
several aspects of code style that contribute to how easy it is to understand code. In this assignment, your
code style will be assessed against the following criteria.
• Readability
– Program Structure: Layout of code makes it easier to read and follow its logic. This includes
using whitespace to highlight blocks of logic.
– Descriptive Identifier Names: Variable, constant, and function names clearly describe what they
represent in the program’s logic. Do not use what is called the Hungarian Notation for identifiers.
In short, this means do not include the identifier’s type in its name (e.g. employee number),
rather make the name meaningful (e.g. employee identifier). The main reason for this
restriction is that most people who follow the Hungarian Notation convention, use it poorly
(including Microsoft).
– Named Constants: Any non-trivial fixed value (literal constant) in the code is represented by a
descriptive named constant (identifier).
• Algorithmic Logic
– Single Instance of Logic: Blocks of code should not be duplicated in your program. Any code
that needs to be used multiple times should be implemented as a function.
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– Variable Scope: Variables should be declared locally in the function in which they are needed.
Global variables should not be used.
– Control Structures: Logic is structured simply and clearly through good use of control structures
(e.g. loops and conditional statements).
• Documentation
– Comment Clarity: Comments provide meaningful descriptions of the code. They should not
repeat what is already obvious by reading the code (e.g. # Setting variable to 0.). Comments
should not be verbose or excessive, as this can make it difficult to follow the code.
– Informative Docstrings: Every function should have a docstring that summarises its purpose.
This includes describing parameters and return values so that others can understand how to use
the function correctly.
– Description of Logic: All significant blocks of code should have a comment to explain how the
logic works. For a small function, this would usually be the docstring. For long or complex
functions, there may be different blocks of code in the function. Each of these should have an
in-line comment describing the logic.
8.3 Assignment Submission
You must submit your assignment electronically via Gradescope (https://gradescope.com/). You should
have received an invitation email welcoming you to Gradescope and asking you to click on a link to set your
password. If you did not receive this email, you can sign up using your UQ email address which is based on
your student number (e.g. [email protected]). When you sign up to Gradescope, you will need
to provide a course entry code. The course entry code for CSSE1001 and CSSE7030 is 6PKYV5. You will
be able to submit until after March 5 but you may sign up before then.
When you login to Gradescope you may be presented with a list of courses. Select CSSE1001/CSSE7030.
You will see a list of assignments. Choose Assignment 1. You will be prompted to choose a file to upload.
The prompt may say that you can upload any files, including zip files. You must submit your assignment
as a single Python file called a1.py (use this name – all lower case), and nothing else. Your submission
will be automatically run to determine the functionality mark. If you submit a file with a different name,
the tests will fail and you will get zero for functionality. Do not submit the a1 support.py or words.txt
files. Do not submit any sort of archive file (e.g. zip, rar, 7z, etc.).
Upload an initial version of your assignment at least a week before the due date. Do this even if it is just the
initial code provided with the assignment. Ensure that you are able to login to Gradescope and upload files
for the assignment. If you are unable access to the course on Gradescope, contact course staff immediately
to ensure that your email address is registered. Excuses, such as you were not able to login or were unable
to upload a file will not be accepted as reasons for granting an extension.
When you upload your assignment it will run a subset of the functionality autograder tests on your
submission. It will show you the results of these tests. It is your responsibility to ensure that your uploaded
assignment file runs and that it passes the tests you expect it to pass.
Late submissions of the assignment will not be marked. Do not wait until the last minute to submit your
assignment, as the time to upload it may make it late. Multiple submissions are allowed, so ensure that
you have submitted an almost complete version of the assignment well before the submission deadline of
20:00. Your latest, on time, submission will be marked. Ensure that you submit the correct version of your
assignment.
In the event of exceptional personal or medical circumstances that prevent you from handing in the
assignment on time, you may submit a request for an extension. See the course profile for details of
how to apply for an extension.
Requests for extensions must be made before the submission deadline. The application and supporting
documentation (e.g. medical certificate) must be submitted via my.UQ. You must retain the original
documentation for a minimum period of six months to provide as verification, should you be requested
to do so.
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8.4 Plagiarism
This assignment must be your own individual work. By submitting the assignment you are claiming it is
entirely your own work. You may discuss general ideas about the solution approach with other students.
Describing details of how you implement a function or sharing part of your code with another student is
considered to be collusion and will be counted as plagiarism. You may not copy fragments of code that
you find on the Internet to use in your assignment.
Please read the section in the course profile about plagiarism. You are encouraged to complete both parts
A and B of the academic integrity modules before starting this assignment. Submitted assignments will be
electronically checked for potential cases of plagiarism.
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