#DOUBLE SIDED BLANK SUDOKU GRID HOW TO#
#DOUBLE SIDED BLANK SUDOKU GRID CODE#

Now, I do really agree with you that, my concern is to further speedup by either re-ordering the techniques or skipping some at some level.

#DOUBLE SIDED BLANK SUDOKU GRID CODE#

Well, I think I reached my limit to optimize the code for speed (no matter how many lines of code required). David P Bird's approach gest a lot of placements without any chance of conflict, which minimizes the the chances of backtracking, while m_b_metcalf's approach allows you to simplify the basic techniques so they take as little time as possible. JasonLion wrote:The largest speedups can be achieved by judicious choice of initial guess placement and optimizing the basic techniques so they are as fast as possible. JasonLion 2017 Supporter Posts: 642 Joined: 25 October 2007 Location: Silver Spring, MD, USA It would be very useful to quantify how many steps are added by backtracking on average, and then compare that to how many steps can be saved on average by using each individual advanced technique.

#DOUBLE SIDED BLANK SUDOKU GRID HOW TO#

On the other hand, if you are setting yourself a puzzle of how to minimize steps as you have defined them, then there are several questions you could ask next. Thousands of very simple steps can be taken in the amount of time consumed by a single step using a more advanced technique. David P Bird's approach gest a lot of placements without any chance of conflict, which minimizes the the chances of backtracking, while m_b_metcalf's approach allows you to simplify the basic techniques so they take as little time as possible.Īnother way to say this is that your count of 'steps' is not a good proxy for time taken. The largest speedups can be achieved by judicious choice of initial guess placement and optimizing the basic techniques so they are as fast as possible. For standard 9x9 Sudoku, using anything more complex than locked candidates will only slow the whole process down.

If you are concerned with the speed of the code, you are indeed headed in the wrong direction. So, the only positive point to include any logical technique is to reduce the backtracking chances.Īs before, that depends on what you are trying to do. With added techniques, took same 47 trial-and-error steps but total 89 steps. It took only 81 steps to complete, including 47 trial-and-error steps. I tested again empty Sudoku grid for first solution with my solver by Naked/Hidden singles and guess-backtracking routine only (and commented rest of the techniques). (As singleton and guess directly fill the cell position as compared to logical steps, which only reduce the chance of backtracking from next step.) The number of logical steps is inverse proportional to guess work. And for that, first reduce the same from empty Sudoku grid, no matter how guess minimize, either by re-ordering the techniques or order of unsolved cell position picking technique (as in David solver case). Rjamil wrote:My idea/question is to implement the techniques/methods in order to reduce the guess work and backtracking.

Double sided blank sudoku grid