## Northwest Airlines Sudoku Puzzles

For fans of Killer Sudoku, Samurai Sudoku and other variants

### Northwest Airlines Sudoku Puzzles

In the DailySudoku forum, there's a question about solving an NWA Sudoku puzzle. If you belong to that forum, you might inform everyone that NWA Sudoku puzzles have extra constraints where four shaded boxes/regions must also have 1-9. This explains why vanilla Sudoku responds with multiple solutions.

Code: Select all
` Shaded Regions +-----------------------+ | . . . | . . . | . . . | | . X X | X . X | X X . | | . X X | X . X | X X . | |-------+-------+-------| | . X X | X . X | X X . | | . . . | . . . | . . . | | . X X | X . X | X X . | |-------+-------+-------| | . X X | X . X | X X . | | . X X | X . X | X X . | | . . . | . . . | . . . | +-----------------------+`

NWA Sudoku puzzles have appeared in this forum as well.

http://forum.enjoysudoku.com/viewtopic.php?p=55881#p55881
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

In fact it is worth mentioning that this form of puzzle, which is more commonly called NRC or Windoku, with the 4 extra explicit shaded regions labelled E,F,H and I, also contains 5 more hidden implicit regions A,B,C,D,G which must contain the digits 1-9. The total of 9 extra regions gives further information useful in solving these problems and in allowing the number of clues to be as low as 11.

Code: Select all
`+-----------------------+ | A B B | B A C | C C A | | D E E | E D F | F F D | | D E E | E D F | F F D | |-------+-------+-------| | D E E | E D F | F F D | | A B B | B A C | C C A | | G H H | H G I | I I G | |-------+-------+-------| | G H H | H G I | I I G | | G H H | H G I | I I G | | A B B | B A C | C C A | +-----------------------+ `
Glyn

Posts: 357
Joined: 26 April 2007

I passed Glyn's comment, about the puzzle being a Windoku, to NWA. I suggested that the puzzle be labeled Windoku instead of Sudoku. They passed my suggestion along to the publishers of their WorldTraveler magazine. The publisher's reply:

Danny,

Thank you for note. We apologize for the confusion. We are replacing the current puzzle with a traditional Sudoku in the September issue. Thanks again for taking the time to express your concern.

Frank Sisser

Side Note: I find it interesting that no one took the time to update the misinformation being passed around in the DailySudoku thread.
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

daj95376 wrote:I find it interesting that no one took the time to update the misinformation being passed around in the DailySudoku thread.

this is the link to their discussion -- "Northwest Airlines"
but we don't have many representatives active in that forum

Pat

Posts: 3964
Joined: 18 July 2005