Just another dimension?

Tuesday, July 11, 2006
Need Help With Sudoku -vwv

I spent most of Sunday sitting at the hospitality desk for the 37th International Physics Olympiad at the Meritus Mandarin. Since most of the international delegates are not at the hotel most of the time, I had a lot of time to spare, so I tried to solve two Sudoku problems.

1. What is the minimum number of blanks a Sudoku puzzle can have and still have more than one unique solution?
2. What is the maximum number of blanks a Sudoku puzzle can have and still have only one unique solution?

Actually, I contemplated problem 2 a long time ago but never really found the answer. And I still could not find the answer after thinking about it for half of Sunday. So I tried to solve the inverse problem, which is problem 1.

Problem 1 was quite easy. It took only a few minutes. The answer is 4 and the proof is not too difficult either.

Out of curiosity, I checked Wikipedia and according to it, problem 2 is unsolved. That sucks. So anyone out there who can solve it please tell me the answer yah, I would really like to know.

-- permalink --
Yiheng made 9:50 PM

0 Comments:




Categories MyLife Opinions OnTheNet Shows Miscellaneous RandomKnowledge Links My Sister S & M Jiangzheng Yiheng's Photos Shuquan's Photos Pei Yee's Photos Yun Qin's Photos #!/usr/bin/girl Archive February 2005 March 2005 April 2005 May 2005 June 2005 July 2005 August 2005 September 2005 October 2005 November 2005 December 2005 January 2006 February 2006 March 2006 April 2006 May 2006 June 2006 July 2006 August 2006 September 2006 October 2006 November 2006 December 2006 January 2007 February 2007 March 2007 April 2007 May 2007 June 2007 July 2007 August 2007 September 2007 October 2007 November 2007 December 2007 January 2008 February 2008 March 2008 April 2008 May 2008 June 2008 July 2008 August 2008 September 2008 November 2008 January 2009 February 2009 March 2009 April 2009 May 2009 June 2009 July 2009 August 2009 September 2009 October 2009 November 2009	Tuesday, July 11, 2006 Need Help With Sudoku -vwv I spent most of Sunday sitting at the hospitality desk for the 37th International Physics Olympiad at the Meritus Mandarin. Since most of the international delegates are not at the hotel most of the time, I had a lot of time to spare, so I tried to solve two Sudoku problems. 1. What is the minimum number of blanks a Sudoku puzzle can have and still have more than one unique solution? 2. What is the maximum number of blanks a Sudoku puzzle can have and still have only one unique solution? Actually, I contemplated problem 2 a long time ago but never really found the answer. And I still could not find the answer after thinking about it for half of Sunday. So I tried to solve the inverse problem, which is problem 1. Problem 1 was quite easy. It took only a few minutes. The answer is 4 and the proof is not too difficult either. Out of curiosity, I checked Wikipedia and according to it, problem 2 is unsolved. That sucks. So anyone out there who can solve it please tell me the answer yah, I would really like to know. -- permalink -- Yiheng made 9:50 PM 0 Comments: Post a Comment	Previous Posts Packed Weekend Part 1 -vvv vvz Categories -vwv Some People Should Conveniently Die Off -vvv vvw Then and Now -vvv Songs and Codes -vvv Church of the Flying Spaghetti Monster -vvx Bad Jokes And Other Deleted Nonsense -vvx My First Stop Motion Animation -vwv A Hundred Million Ducks -vwv China in Black and White -vvv vwv Current Read 七侠五义 Last Three Books 道德經 The Ultimate Encyclopedia of Mythology Arthur Cotterell, Rachel Storm Momo Michael Ende Those Before 孫子兵法 Paycheck: And Other Classic Stories By Philip K. Dick Mirror Mirror: A Novel Gregory Maguire American Gods Neil Gaiman Maya 5 Fundamentals Garry Lewis, Jim Lammers Harry Potter and the Order of the Phoenix J. K. Rowling