Sudoku

Sudoku is a puzzle that has been found in most newspapers since it gained popularity in 2005. Typically, the puzzle is played with a 9x9 grid that is subdivided into nine 3x3 boxes. The object of the puzzle is to fill the grid such that the digits 1 to 9 are contained (without repeats) in each row, each column, and each box. Seed digits are initially placed in the grid to define the puzzle and to limit where additional digits can be added by the person solving the puzzle. For this assignment, you are going to make a simple, digital version of a Sudoku game.

Setup

Create a directory assignment1 under assignments in your cs170 directory. All code for the assignment should be stored in this directory.

cd ~/cs170/assignments
mkdir assignment1 
cd assignment1

Details

You are going to be using the Tkinter module to create a graphical version of the Sudoku game. Your program will read a text file that encodes the initial seed values for the Sudoku puzzle, and allow users to change the non-seed values by clicking on the appropriate cells. You do not need to worry about whether the user has won the game, just allowing them to play the game is fine.

The text file will contains 9 lines of 9 characters each. Each character specifies the value of a given cell in a Sudoku puzzle. Values in the range [1,9] specify that cell contains a "seed" value for the puzzle, while a value of 0 specifies that cell is initially empty. For example, the following text file represents the Sudoku puzzle shown above.

002300050
010040000
900005020
800760030
700000004
060034005
050200006
000010070
070009800

When the user clicks on a cell of the puzzle that was not originally a "seed" value, the value of the cell should be incremented by 1. For example, an empty cell would get assigned the value of 1, while a cell with a value of 5 gets the new value of 6. Cells with a value of 9 should become empty. Nothing should happen if the user clicks on a "seed" value.

Pseudocode

One important skill we hope to get across this semester is how much starting on paper actually helps write programs. We are going to force you to do so starting with this assignment.

For Wednesday, January 27^th, ON PAPER perform the top-down design discussed in class on Monday for this assignment. You must have a good outline of the "main" portion of your program by Monday. For any sufficiently complicated block of code, define a function and write the Pre and Post conditions for the functions. You do not have to have written the function bodies by Monday, but it should be obvious how to write the function bodies based on the Pre and Post conditions.

These are worth 30 points of your assignment grade. They will be graded 50% on completion, and 50% on correctness. It does not sound like a lot, but they should be 30 easy points to get each week. Do not neglect them.

I will provide a top-down design of the program in class on Wednesday.

Submission

You are required to submit a tar file to http://inquire.roanoke.edu/. On cseval, there is a link for Assignment 1. You can create a tar file by issuing the following commands:

cd ~/cs170/assignments
tar czvf assignment1.tgz assignment1/

"Hacker" Prompt

Each week, additional exercises related to the assignment will be provided at the end. These exercises are typically more challenging than the regular assignment. Bonus points will be provided to students who complete any of the "Hacker" level assignments.

1. Conflicts: The rules for Sudoku are very clear. Yet, most people still end up trying to write invalid moves to the board. Even if the conflict already exists. It would be advantageous to the users for you to notify them of a conflict in some way.

   You should highlight all cells that are currently in conflict with some other cell.

2. Winning: The standard portion of this assignment does not require you to notify the user if they won. Presumably your users are intelligent enough to notice if they won, but not all users will be able to.

   Modify your program so that it displays a text message to the user indicating that they successfully completed the puzzle.

3. Saving and Loading: Some people take a long time to solve a single Sudoku puzzle. Long enough that it would be advantageous for them to be able to save the current state of the puzzle, to load their progress later.

   Bind the 'S' key to save the current state to a file. Bind the 'L' key which loads that state to the game. This should be a specifically named file, so only one save will be active at any given time.

   Don't forget to make sure that the values the user enters into the game are not loaded as seed values!