SudokuSolver Forum

Here is puzzle #28 from the now-defunct Sudoku Magazine's Sudoku Mix #1. As you can see from the second image, I've gotten stuck. SudokuSolver gives me errors when trying to get hints or solve (from either point), although it says its a valid puzzle. Am I doing something wrong or missing something, or is there something wrong with the puzzle itself? (I'll address the SudokuSolver errors in another thread.) The puzzle code:

Hi Enxio

I tried this jigsaw, after seeing your post, and initially managed to get only slightly further than you did. From Law of Leftovers on R123 R4C129 must be {239} because 6 already placed in R5C9, so R4C5 = {78}.

The only way I was able to get further was using bifurcation, because I'm not very good at complicated wings (anything more than X-wings) or "fish". I looked at 7 and 8 for R4C5 and 7 gave me two 8s in C8. Then with R4C5=8 I tried 2 and 5 in R1C1; 2 didn't work for the upper-centre nonet where I couldn't place a 2, then R1C1 = 5 gave a valid solution for this puzzle.

As for the behaviour of SudokuSolver, it was strange. When I first set up the puzzle it was able to score it and solve it. However when I saved the puzzle and later reloaded it, SS wasn't able to score it or solve it.

When it scored it from the original set up position it gave a score of only 1.0 and said it used a XY-wing. Maybe that's what's needed to solve it from the position which you reached? I don't know enough about XY-wings to spot one in the position you reached.

I just tried the same puzzle in JSudoku, and got the same results that I got manually, except that it also eliminated an 8 from R4C1 and a 2 from R4C5 for reasons I wasn't able to determine from the JSudoku log. Otherwise, JSudoku didn't get any farther with the puzzle than you or I did.

I even double- and triple- and quadruple-checked the puzzle against the original, just to make sure I hadn't made a mistake in copying it to SudokuSolver.

I'm inclined to chalk this one up to the fault of the puzzle creator/publisher and call it a day.