Stuck with an hard puzzle on my iPhone (Amazing Sudoku)

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Stuck with an hard puzzle on my iPhone (Amazing Sudoku)

Postby cLin » Mon Nov 17, 2008 2:11 pm

Can someone guide me on what my next step should be? Preferably by telling me to look at X row/col by using a certain techniques. I know most of the techniques from Basic Fish on up on this and I'd like to learn how to use more.
Code: Select all
7 . . | 4 . . | . . .
. 2 . | . . . | . . 3
. . . | . 5 . | . . .
------+-------+------
. . . | . 8 . | . 9 4
. . . | 7 4 5 | 6 . .
8 4 . | 1 . . | . . .
------+-------+------
. . . | . . 4 | . . .
4 . 9 | . . 2 | . 3 .
1 3 6 | 9 7 8 | 5 4 2


Normally, the hard puzzles in the app aren't too hard for me (takes me 20-30 mins:( ) but I don't know where to proceed on this.
cLin
 
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Postby storm_norm » Mon Nov 17, 2008 3:50 pm

might be because the puzzle in the state that you posted has multiple solutions. are you sure you posted the puzzle with all givens correctly?
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Postby cLin » Mon Nov 17, 2008 8:12 pm

to be honest, no. I saved a screenshot of it with some of my answers inserted already. Could be one of my inserts could of been false. Darn.
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Postby m_b_metcalf » Mon Nov 17, 2008 9:26 pm

cLin wrote:to be honest, no. I saved a screenshot of it with some of my answers inserted already. Could be one of my inserts could've been false. Darn.

Possibly, but by adding a wrong value to a valid puzzle you cannot increase the number of solutions from one to many, but only reduce the number from one to zero. You can go from one to many by leaving out a clue.

Regards,

Mike Metcalf
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Postby eleven » Tue Nov 18, 2008 6:51 am

Probably it was this one:
Code: Select all
 +-------+-------+-------+
 | 7 . . | 4 . . | . . . |
 | . 2 . | . . . | . . 3 |
 | . . . | . 5 . | . . . |
 +-------+-------+-------+
 | . . 7 | . 8 . | . 9 4 |
 | . . . | 7 4 5 | 6 . . |
 | 8 4 . | 1 . . | . . . |
 +-------+-------+-------+
 | . . . | . . 4 | . . . |
 | 4 . 9 | . . 2 | . 3 . |
 | 1 3 6 | 9 7 8 | 5 4 2 |
 +-------+-------+-------+
There is a hidden pair in row 6.
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Postby m_b_metcalf » Tue Nov 18, 2008 10:33 pm

eleven wrote:Probably it was this one:
Code: Select all
 +-------+-------+-------+
 | 7 . . | 4 . . | . . . |
 | . 2 . | . . . | . . 3 |
 | . . . | . 5 . | . . . |
 +-------+-------+-------+
 | . . 7 | . 8 . | . 9 4 |
 | . . . | 7 4 5 | 6 . . |
 | 8 4 . | 1 . . | . . . |
 +-------+-------+-------+
 | . . . | . . 4 | . . . |
 | 4 . 9 | . . 2 | . 3 . |
 | 1 3 6 | 9 7 8 | 5 4 2 |
 +-------+-------+-------+
There is a hidden pair in row 6.

Very likely. The posted version had 22 solutions, with these 46 clues in common:
Code: Select all
  7 . 3 4 2 . . . .
 . 2 . 8 . . 4 . 3
 . . 4 3 5 . 2 . .
 . . . 2 8 3 . 9 4
 3 9 . 7 4 5 6 . .
 8 4 . 1 . . 3 . .
 2 . 8 . 3 4 . . .
 4 . 9 . 1 2 8 3 .
 1 3 6 9 7 8 5 4 2

It has to be one of those missing, which yours is.

Regards,

Mike Metcalf
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Postby eleven » Wed Nov 19, 2008 3:43 am

m_b_metcalf wrote:It has to be one of those missing, which yours is.

.. and its the only one i found, which made it unique without having a single as the first move.
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