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At the end of the project, I analyzed the relationship between the number of initial values and the performance of the solver by running a large number of simulations.

2. Board Class

The Board class holds the array of Cells that make up the Sudoku board. It is able to read a board from a file, test if a value is valid at a certain position on the board, and test if the board is solved.

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The validSolution() method returns true if the board is solved. I did this by looping over all of the Cells on the board. 

 

3. Sudoku Class

The Sudoku class has a constructor that creates a board and a solve method so that it can solve a puzzle.

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To handle the special case where the next Cell is on the next row, I use an if statement to check the location of the Cell.

 

4. LandscapeDisplay Class

The LandscapeDisplay class creates a visualization of the board. I implemented draw() methods in my Board class and Cell class. 

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The draw() method in the Cell class draws the Cell's number. I used the Graphics drawChars method to draw a character.

 

 

5. Exploration

  1. What is the relationship between the number of randomly selected (but valid) initial values and the likelihood of finding a solution for the board? For example, if you run 5 boards for each case of 10, 20, 30, and 40 initial values, how many of each case have a solution?

         

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When the number of initial values is between 20 and 25, the relationship is random and not linear.

 

6. Extension

1) Make the visualization fancier.

Firstly, I modified the LandscapePanel class and changed the background color to black. 

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Finally, I drew lines to separate the big grid into 9 sub-grids, as explained above.

 

2) Add a button to reset the board and do a new solve. Add output statistics.

In the LandscapeDisplay class, I added two JButton objects to solve and reset a Board.

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And then I can solve the board again.

 

3) Automate the process of exploring the trends in the simulation. An automated process should be able to analyze the results of hundreds of games.

I created a new Automation class with a method auto() that returns a String showing the results of games and a main method that takes in command line arguments and prints the String returned by auto().  

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The average steps taken to solve a board fluctuates but generally increases as the number of games becomes larger.

 

4) Enable your read method to handle the files with extra spaces.

I modified my read() method in the Board class to handle files that have extra spaces and lines. The big idea is to replace the spaces with empty strings.

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The output in the terminal is shown below:

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5) Identify in comments when dynamically allocated memory is being "lost." Dynamic memory is any memory created with a new command. Indicate the line of code in which the last reference to an object referencing dynamic memory is removed.)

CellStack.java   line 36

 

7. Reflection

From the project, I learned the new data structure–stacks and how to use backtracking to build a solver. However, the algorithm is inefficient regarding the time taken to solve a board. It was challenging but interesting to handle the details in designing a Board and a game of Sudoku. 

8. Collaboration

Professor Layton

Professor Maxwell

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