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08 April 2009 @ 08:24 pm
Spot The Differences (Redux)  
So tonight I'm putting together a packet of "Not Sudoku" Puzzles for the WSC in two weeks (where it seems both Wayne Gould and Maki Kaji will be making guest appearances).

In putting together this hand-out, I realized it was time to fix the one puzzle that I had made overly difficult based on an error in my multi-cell subtraction considerations. I've made a much better subtraction-only puzzle that actually has a fair solution path.

motrismotris on April 12th, 2009 01:36 am (UTC)
Great! Since no one has done it yet, here is the quick walkthrough from me:

The 3- in the rightmost column forces the bottom two cells in the three-cell region to be a 3- as well (14), (25), or (36), and with any of these for 2- overall, the extra cell in column 5 is a 1. (This part of the walkthrough should be familiar from before).

Now, the fifth column has another pair of 3-'s which makes the top value, R1C5, a 4. The remainder of the puzzle can be solved by recognizing that two 2- cells in a row means one must be "even with a 4" and one "odd with a 3". The 2- with the 4 in row 1 has a 2 or 6 left, but the other one must be 3 and 1 or 5. However, the second column must have the same "odd with a 3" and "even with a 4" in its 2- cages, so R1C3 must be 3 and R6C2 is 2 or 6.

With the 3 in R1C3, you can show column 3 has the 3- as {14}, the 1- as {56}, and the bottom cell is 2 (making R6C2=6). It trickles out from there, but the placement at R1C3 is the "improved" solution path I intend with an interesting but hard deduction.

cyrebjrcyrebjr on April 15th, 2009 01:03 am (UTC)
You switched the 2 and 6 in the last row. No biggie, though.