The difficulty of the generated puzzle is then provided to the user. After a few attempts if the program is unable to remove additional cells without making the puzzle unsolvable it stops. It then tries to remove a different pair of cells. When it finally gets to the point where the puzzle can’t be solved it fills the values back into the last two cells it removed. The two cells are removed and the solver is run. the cell in the upper left and the lower right) while making sure the puzzle is still solvable. At this point I keep removing a cell and its mirrored pair (e.g. I’m sure there’s a more efficient way to fill these out but this works pretty well and doesn’t take too much time. This works properly most of the time but if it gets stuck then I just clear it all out and start over again. From there I can run the Solver to fill in the remaining four big boxes. If it gets stuck then it just clears out the entire corner box and starts over again. The code determines which values are allowable and tries to fill them in. At this point I can’t randomly assign values because the other two corner boxes restrict where the numbers can be used. Next, I fill out the big boxes in the remaining two corners. To start I fill out the three big boxes along the diagonals by inserting the numbers 1 through 9 at random.

all nine numbers in each row, column, and 3x3 big box). The first thing I need is a completed puzzle that meets all the restrictions of Sudoku (e.g. I found several methods online but wasn’t thrilled with any of them so I decided to create my own concept.

Generating a puzzle is tricky and involves more trial and error than solving a puzzle.

With this is mind I updated my previous Excel file so that it can generate Sudoku puzzles as well as solve them. There seem to be far fewer Sudoku Generators, that can create the puzzles in the first place. When I first posted my Sudoku Solver I mentioned that there are many such programs available.

Sudoku solver excel microsoft