HoDoKu simple solve but HoDoKu says sorry can't solve
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#264 HoDoKu simple solve but HoDoKu says sorry can't solve
yesterday I had a Sudoku with 3 unusual squares...
I wanted HoDoKu to give me a hint but HODoKu said sorry, no more hints possible.
Remaining possibles of three corners of one rectangle were 1 and 5 and the fouth corner has 1,5 and 9 as possibles.
HoDoKu should have told me...unusual square and should have eliminated 1 and 5 as possibles from the 1,5, and 9 field but it didnt... HoDoKu was running out of possible options for such an easy solve.
INCREDIBLE
Something like the attached image. HODoKu didnt have a solution.
Here it is
Perhaps the problem is that Givens were not established. Maybe try that first and see if HoDoku can proceed beyond this point. As it stands, I get the message it's an invalid puzzle having multiple solutions. Nonetheless, fyi, Find All Steps does display appropriate solutions.
Actually, other sudoku solvers have no problems with that situation.
The fact is the puzzle has no single solution. HoDoKu at least recognises that and therefore does not, cannot, offer only one solution. Other solvers may seem to do so, but there is no right answer. r2c7 = 1 or 9, depending how you look at it.
other programs solve it and there seems to be only one solution.
For another sudoku Andrew Stewart's solver cracks it only offering one Y-Wing while this solver first goes through TWO much more complicated moves.
I'm not familiar with Andrew Stewart's solver, but I did find it as a web application. What do you mean, "another sudoku"? For the one under discussion, Andrew Stewart's solver does not use a (X)Y-Wing for the simple reason that it doesn't apply. Like HoDoKu, Andrew Stewart's solver shows Unique Rectangles as the next steps. It seems to show only one solution due to ignoring another overlapping Unique Rectangle.
In fact, "Solution Count" on that page proves the puzzle to be invalid. A valid puzzle wiill have one solution only - not 21!
Another Sudoku as in another one and not this one.
I had a Sudoku from a booklet, entered it into the HoDoKu solver first and it came up with some very complicated extreme solutions.
When I entered the same puzzle into the Andrew Steward solver the solver found a Y-wing and then it practically fell apart (as in no further difficulties, all singles or hiden sinles.)