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| Simes
 | | Joined: 08 Apr 2005 | | Posts: 71 | | : | | Location: North Yorkshire, UK |
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 Posted: Sat Apr 09, 2005 9:05 pm Post subject: rubylips - X-Wings examples |
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Hi rubylips,
I've been using your xwing examples from the google group to test my implemention, but, after an excess of alcohol, I can't find the x-wing in examples 1 and 4. Could you point me in the right direction?
| Code: | X-Wing 1
...13...5
.4....2..
8..9.....
....5.9..
..2...4..
..3.6....
.....3..6
..5....1.
7...28...
X-Wing 4
.....8..7
3.4......
..9.15...
.......6.
5..7.2..3
.8.......
...69.4..
......9.1
2..3..... |
Simes |
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| rubylips
| | Joined: 07 Apr 2005 | | Posts: 62 | | : | | Location: London |
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| Posted: Sun Apr 10, 2005 1:20 am Post subject: |
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Puzzle 1:
| Code: | . . . | 1 3 . | . . 5
. 4 . | . . . | 2 . .
8 . . | 9 . . | . . .
----------------------
. . . | . 5 . | 9 . .
. . 2 | . . . | 4 . .
. . 3 | . 6 . | . . .
----------------------
. . . | . . 3 | . . 6
. . 5 | . . . | . 1 .
7 . . | . 2 8 | . . . |
After 7 moves:
| Code: | . . . | 1 3 . | . . 5
3 4 . | . . 5 | 2 . .
8 5 . | 9 . 2 | . . .
----------------------
. . . | . 5 . | 9 . .
. . 2 | . . . | 4 . .
. . 3 | . 6 . | . . .
----------------------
. . . | . 1 3 | . . 6
. 3 5 | . . . | . 1 .
7 1 . | . 2 8 | . . . |
whereupon the solver tells us:
The value 1 in Box [2,1] must lie in Column 1.
The value 6 in Box [1,3] must lie in Column 7.
The value 8 in Box [1,3] must lie in Row 1.
The value 8 in Box [3,3] must lie in Row 8.
The value 9 in Row 8 must lie in Box [3,2].
6s must appear in the cells (2,3) and (9,4) or the cells (9,3) and (2,4).
The cell (3,7) is the only candidate for the value 6 in Row 3.
The observation 'The value 6 in Box [1,3] must lie in Column 7' is critical because it eliminates (2,8) as a candidate for 6, which leaves just two candidate positions in each of Rows 2 and 9.
Puzzle 4:
| Code: | . . . | . . 8 | . . 7
3 . 4 | . . . | . . .
. . 9 | . 1 5 | . . .
----------------------
. . . | . . . | . 6 .
5 . . | 7 . 2 | . . 3
. 8 . | . . . | . . .
----------------------
. . . | 6 9 . | 4 . .
. . . | . . . | 9 . 1
2 . . | 3 . . | . . . |
After 30 moves:
| Code: | . . . | 9 3 8 | . 4 7
3 . 4 | 2 7 6 | . . 9
8 7 9 | 4 1 5 | 3 2 6
----------------------
. . . | . . 9 | . 6 .
5 . 6 | 7 . 2 | . 9 3
9 8 . | . 6 3 | . . 4
----------------------
7 . . | 6 9 1 | 4 . 2
. . . | . 2 7 | 9 . 1
2 9 1 | 3 . 4 | 6 7 . |
whereupon the solver tells us:
The values 2, 3 and 7 occupy the cells (4,2), (4,3) and (4,7) in some order.
The values 2 and 7 occupy the cells (6,3) and (6,7) in some order.
The values 4 and 6 occupy the cells (8,1) and (8,2) in some order.
The value 5 in Box [1,3] must lie in Column 7.
5s must appear in the cells (4,5) and (9,9) or the cells (4,9) and (9,5).
which follows from inspection of Columns 5 and 9.
Unfortunately, the discovery of the X-Wings isn't sufficient to solve the problem. We must revert to Nishio in order to deduce the next move:
The move (2,2):= 1 would make it impossible to place the remaining 1s.
The value 5 is the only candidate for the cell (2,2).
The solver at http://act365.com/sudoku should detect X-Wings correctly. |
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| Simes
| | Joined: 08 Apr 2005 | | Posts: 71 | | : | | Location: North Yorkshire, UK |
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| Posted: Sun Apr 10, 2005 8:54 am Post subject: |
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| Thanks - I've sorted it out now. |
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