[Feature Request] Automatically compute pencil marks

[andbenn]

As a user, I'd like to save half of my game duration play time, and have the pencil marks for the current board computed and displayed.

There may be cases where I started and have a error I don't see, and pencil marks can't be computed. An error or requirement that pencil marks can only be computed at start or first is ok.

[arifz]

Some suggestions for a partial implementation of the auto-fill pencil marks

My way of pencil marks is to select a digit and then pencil in all the possible places where it could possibly be. Sometimes the digit is entirely missing, in which case I have to enter that digit in all the open squares. At other times, there are only one or two of that digit present on the initial board. Even in that case, it would be helpful to have a button which could fill all the square with the chosen digit, after which I could remove the few places which are not possible, by simply removing one row one column and one box.

For the extreme case, if you simply count how many moves it takes, I am sure that if I started from a board where all the digits were penciled in, in all the empty squares, it would take less time to remove the unwanted marks, than it does to start from a blank board where we pencil in all the marks.

[manuelliebchen]

I would second this. Especially when playing 16x16 Sudokus it takes a lot of time filling in all the trivial candidates and it is frustrating when there is an error in it.