I have a question about Sudoku

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I have a question about Sudoku

Postby Sixteen » Sun Feb 24, 2008 7:14 pm

Hi, I'm new, and I have a question about Sudoku.
I know that the least numbers needed to have one solution is 17, but what is the least amount of numbers to have 2 solutions? Or the most numbers to have 2 solutions?
Sixteen
 
Posts: 1
Joined: 24 February 2008

Postby JPF » Sun Feb 24, 2008 8:32 pm

Hi Sixteen, welcome to the forum.
There is no certainty about 17, just a conjecture.
See here for the answers :

16 clues :
Code: Select all
 5 . 2 | . . . | 4 . .
 . . . | 7 1 . | . . 3
 . . . | . . . | . . .
-------+-------+-------
 . . . | . . 4 | 6 . .
 . 7 . | 2 . . | . . .
 . 1 . | . . . | . . .
-------+-------+-------
 6 . . | . . 2 | . . .
 . . . | . 3 . | . 1 .
 4 . . | . . . | . . .

77 clues :
Code: Select all
 1 5 9 | 2 8 6 | 4 7 3
 2 3 7 | 1 5 4 | 8 9 6
 4 8 6 | 3 9 7 | 5 2 1
-------+-------+-------
 9 1 2 | 8 4 3 | 7 6 5
 3 4 5 | . . 9 | 1 8 2
 6 7 8 | 5 2 1 | 3 4 9
-------+-------+-------
 8 6 1 | 4 3 2 | 9 5 7
 5 9 3 | . . 8 | 2 1 4
 7 2 4 | 9 1 5 | 6 3 8

These 2 puzzles have 2 solutions.

JPF
JPF
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Joined: 06 December 2005
Location: Paris, France

Postby ab » Mon Feb 25, 2008 1:32 am

please let us know if you find a 15 clue puzzle with just two solutions. You could then add one clue and have a 16 clue valid puzzle:!:
ab
 
Posts: 451
Joined: 06 September 2005


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