3
$\begingroup$

37x3412xx

I have tried every trick I can think of... where am I going wrong?

$\endgroup$
  • 1
    $\begingroup$ Why wouldn't you be able to switch the one and the seven in the middle left box and then also switch the two and seven in the middle right box? $\endgroup$ – PotatoLatte Jul 27 '18 at 0:33
  • 1
    $\begingroup$ @ZaniXu In the middle-right box, the 1 can only be on the second line. That's why you cannot put the 1 on the second line of the middle-left box. $\endgroup$ – xhienne Jul 27 '18 at 1:17
  • $\begingroup$ plz see: puzzling.meta.stackexchange.com/questions/6418/… $\endgroup$ – JMP Jul 27 '18 at 1:55
3
$\begingroup$

You have an X-cycle - both the options for 5, the green 5's and the purple 5's, eliminate the yellow 5.

enter image description here

From http://www.sudokuwiki.org/sudoku.htm

$\endgroup$
  • $\begingroup$ The solver doesn't actually solve any cells until it performs an "Alternate Inference Chain", though. $\endgroup$ – Riking Jul 27 '18 at 4:31
2
$\begingroup$

Top row, first empty cell : there are two possibilities 8 and 9

If it is an 8, there is no other 8 in the top-left region
If it is a 9, other empty cells in the same row are respectively 6 and 8. Then last two empty cells of the second row are respectively 9 and 3. Fifth cell of the second row is then an 8.
Therefore in either case, there is no 8 in the first two empty cells of the second row. First empty cell of the second row is then a 2.

You can also use the same reasoning to eliminate other possibilities. In the central cell of the middle-left region there are two possibilities : 4 and 6

If it is a 4, there is no other 4 on the same row
If it is a 6, there is a 5 in the highlighted cell (the blue one in the top-left region). Then there is a 4 in the second empty cell of the middle line.
Therefore in either case, there is no 4 in the central cell (middle region), or in the first empty cell of the sixth line.

And so on...

$\endgroup$
  • 1
    $\begingroup$ Thanks everyone! I actually ended up just doing trial and error- ended up being easier in the end 🙄 $\endgroup$ – Rizza354 Jul 27 '18 at 15:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.