World of MindStorms

Read more about my Sudoku game here: part 1, part 2, part 3, part 4

Although I spent most of today packing for vacation (you probably won’t see too many updates on this site the coming three weeks), I managed to squeeze in a couple of hardcore programming hours, which allowed me to finish a first working version of my sudoku game. Some screen shots:

So here’s how it works:

1. The user selects a difficulty (the higher the difficulty, the less visible clues) using the left and right arrow keys and then clicks the orange button
2. A completely random Sudoku is generated and displayed on the screen
3. The arrow keys are used for navigating the grid: the left key moves the cursor over one spot to the left, and the right arrow key moves the cursor down one spot. If the user reaches a side/ corner, the next arrow click will bring the cursor to the other side of the playing field, as illustrated below:

4. Clicking the square orange key when an editable cell is selected (“clue” cells aren’t editable) will increment the cell’s value by 1, unless its value is 9, in which case the cell will be reset to 0
5. Clicking the rectangular gray key will check the user’s version of the sudoku against the answer key (a copy of the generated sudoku without the non-clue cells removed), and tell the user how many errors there are. If there aren’t any, a “You win!” message will appear and the program will be aborted; if there are errors (including un-solved cells), the user will be asked if he/ she wants the wrong cells reset — if yes, the program will clear these cells, if no, they’ll remain wrong and the user will return to the game

So overall I’m very pleased with the game, because it was quite challenging to make it work doing some pretty difficult things, such as:

• Generating a completely random Sudoku from scratch every time the program runs
• Deciding which cells could safely be hidden from the user while still keeping the Sudoku solvable
• Making a custom, smaller, font for the NXT to be able to show a grid around the numbers.

Anyways, if you’d like to download the most current code for this project, see this page here:

https://sourceforge.net/projects/dimastero/files/Sudoku/?

Changelog:

• v1.0.0 (7/27/2012) Initial release
• v1.0.1 (7/27/2012) Added documentation

Read more about my Sudoku game here: part 1, part 2, part 3, part 4

Read more about my Sudoku game here: part 1, part 2, part 3, part 4

Especially after the program got up to the point of being able to hide parts of the Sudoku from the user, the grid that was being displayed wasn’t very clear; it was hard to see what numbers were together in the 3*3 blocks.

The obvious solution was to simply place a grid around it, but, with the 64*100 pixels screen and the 7 pixel high font, that didn’t work. So instead, I made my own font for displaying digits to the screen, which is featured in the picture below.

Writing pseudo code for this would be a waste of time, but the general idea is that the function makes a black rectangle, 5 pixels high and 3 pixels wide, and then uses a couple of for loops to erase parts of it again.

Here’s a link to the RobotC function: [LINK]. I would’ve put it here, but the formatting thought different.

Next, I’m going to make a way for the users to be able to select cells in the Sudoku, move to different cells, and fill in numbers in those cells. And then all that’s left is checking the user’s score.

Read more about my Sudoku game here: part 1, part 2, part 3, part 4

Read more about my Sudoku game here: part 1, part 2, part 3, part 4

Today I got some more work done on the Sudoku game for Mindstorms NXT: the program is now able to smartly hide parts of the complete Sudoku grid, leaving necessary clues.

The way the removal code works, it goes to a random position on the grid a number of times depending on the difficulty, and then uses two solving methods to check how many numbers would fit in that spot. If more than 1 fit, it means that the user would not be able to solve for that cell, so the number is kept as a clue; if only 1 number fits, however, the cell is hidden from the grid to be solved by the user. Here’s the pseudo code for the hiding part:

1. Copy the full Sudoku grid from the sudoku array to the userSudoku array (the former will be kept as an answer key)
2. Enter the outer for loop that repeats difficulty times (the harder the puzzle, the more clues need to be hidden; default is 30)
3. Reset the tries variable
4. Increase the tries variable by 1
5. Check whether the tries variable is above 100. If it is, skip forward to displaying the Sudoku; if not, continue
6. Reset all the Boolean variables in the numbers array to true
7. Set variables j and k to random numbers between 0 and 8
8. Check whether userSudoku[j][k] is equal to 0. If it is, go back to step 4; if not, continue
9. Enter a second level for loop that determines l and repeats 9 times
10. Enter a third level for loop that determines m and repeats 9 times
11. Check whether userSudoku[j][m] is equal to l. If it is, set numbers[l] to false
12. Exit the second and third level for loops
13. Enter a second level for loop that determines l and repeats 9 times
14. Enter a third level for loop that determines m and repeats 9 times
15. Check whether userSudoku[m][k] is equal to l. If it is, set numbers[l] to false
16. Exit the second and third level for loops
17. Check how many variables of the numbers Boolean array are true. If this is 1, set userSudoku[j][k] to 0; if not, go back to step 4
18. Exit the outer for loop

So this results in the program setting a number of cells in the userSudoku grid to 0 (and all cells equal to 0 aren’t displayed) and thereby hiding parts of it from the user’s view, creating an actual Sudoku puzzle, like the ones in the screen shots above and below.

The next step is to make smaller text for the NXT, because, the way it is now, the numbers are too close together and I can’t display a grid around them (there is only a little screen estate available; 64*100 pixels). This won’t be too difficult though, because I’ll only need to make single digits (0, 1, 2, 3, 4, 5, 6, 7, 8 and 9).

Read more about my Sudoku game here: part 1, part 2, part 3, part 4