mercredi 27 février 2013

Grille de la semaine #20 [League of Extraordinary Ladies and Gentlemen #7]

La League of Extraordinay Ladies and Gentlemen est entrée dans sa huitième semaine d'existence et ceci est ma septième contribution à cette initiative sans précédent et qui est loin de s'essouffler au vu de la qualité et de l'originalité des grilles proposées. La grille de la semaine est mon premier essai de Greater Than Killer Sudoku, une variante peu commune dans le milieu compétitif (au contraire de sa proche cousine la Greater Than And Killer Sudoku, popularisée en particulier par le site fed-sudoku) et traditionnellement associée à une difficulté élevée. J'ai tenté de rompre avec cette habitude en proposant une grille plus abordable que la moyenne du genre.
Je crains fort d'avoir échoué.

Today's puzzle is a Greater Than Killer Sudoku, which must not be confused with its cousin Greater Than And Killer. Here, the relations depict (in)equalities between the cages and not the digits. This particular puzzle was supposed to be rather easy at first. Actually, I am afraid it isn't - but of course I may be overestimating its difficulty. I know other authors who have a tendancy to estimate strangely the difficulty of their puzzles. Oui, c'est à toi que je pense, Tom !

Règles :
Chaque ligne, colonne et région doit contenir les chiffres de 1 à 9.
La somme des chiffres de chaque zone délimitée doit respecter les égalités et inégalités.
°°°°°°°°°°°°°°°°°°°°
Each row, column and region must contain the digits from 1 to 9.
The sum of digits within each cage must obey the equality and inequality signs.

#22 Greater Than Killer Sudoku

 

12 commentaires:

  1. I'm sure I don't know what you mean :)

    That said, sometimes there are nice short-cuts. For example with the non-consecutive I posted a couple of weeks ago, you could use uniqueness to write down the solution in less than a minute. The odd wasn't so bad once you spotted a (relatively easy!) x-wing. Perhaps I was wishing the pain I felt trying to get that to have a valid solution upon my solving audience a little too much!

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  2. Actually I didn't use the x-wing you mention, only pairs, triplets and even a quadruplet (!) if I remember well. Of course the difficulty of a puzzle is far from being something absolute; in the case of your odd sudoku, I found the solving to be pretty similar to the one of a hard classic, and these are one of my strong points - so it is only natural that I was quick on it. But I would be a liar if I pretend that I found it "easy". ;)

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  3. I could not find the starting here?!Can you give me the spoiler.I have tried for a long time .No use of pencil marks in this sudoku.This sudoku is beyond all that.

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  4. This variant is indeed quite hard if you are not used to it. Obsiously, the first thing to do is to try to deduce the value of some areas, or at least to restrict the possibilities as much as possible for these areas.

    Spoiler behind!

    ------------------------------

    The key here is to consider region 6. This region is made of four areas of equal value (let's call them A, B, C and D), plus one cell. Since the sum of all digits in a region is always equal to 45, this leaves us with few possibilites: 4x9+9; 4x10+5; 4x11+1.
    Now, have a look at the area (E) to which belongs the "alone" cell of region 6: its value is inferior to the one of A/B/C/D, therefore <11. Meanwhile, it is equal to the one of the square-shaped area made of four cells in region 9. The minimal value for this area being 10 (1+2+3+4), we now know that E is strictly inferior to 11 but at least equal to 10. Hence, E=10 and A/B/C/D=11.
    This gives you the value of most of the areas, as well as cells R6C7 and R7C7.

    There are still things to see, so feel free to ask again if you get stuck - but at least now you got some numbers to play with!

    Hope it helps,

    Bastien

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    Réponses
    1. Hallo Bastien
      I got stuck with this one... I found alle the values of the areas in Region 1,4,5,6,7,8,9 and the value of R6C7, R7C7 and R4C2, but how do I find the value af the areas in Region 2 and 3... I can see that the value should be either 10,11,12 or 13 - but how to move on...

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  5. Thnks Bastien for the nice tips .Hope to complete this greater than killer using these tips.All your sudokus are very innovative.Great fun while solving especially the diagonal sudokus!

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  6. Hallo Bastien
    I got stuck with this one... I found alle the values of the areas in Region 1,4,5,6,7,8,9 and the value of R6C7, R7C7 and R4C2, but how do I find the value af the areas in Region 2 and 3... I can see that the value should be either 10,11,12 or 13 - but how to move on...

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    Réponses
    1. Hey,
      Sorry for the delay, I had prepared an answer but it got lost in the limbos of Internet. There are indeed a few more things to see, and it isn't that obvious to determine where you have to look.
      - First things first, you can easily place a 9 in region 8; this will be useful later on.
      - Then, notice that in region 5, the 1 will be either in R5C4 or in R5C6.
      - We know the sum of R4C4/R5C4/R6C4 is equal to 45-11-11-10=13. Moreover, the value of R4C4 is equal to 7 at most, and R6C4 is either a 2 or a 3; meaning that R4C4+R6C4 will be 10 at most, hence R5C4 has to be superior or equal to 3. Conclusion: in region 5, R5C6=1 and R6C6=9.
      - You can make some progress from this point, but there is still a hard step ahead. Look at column 7: due to the "10" area in region 9, the 2 in this particular column has to be in region 3, which means it will belong to one of these areas of unknown - and equal - value. This restricts their value to 11 at most.
      - Now, back to the 9s we placed earlier in regions 5 and 8. In region 2, the 9 seems to have three potential cells to go in, but are R1C4 and R2C4 still acceptable now that we know that the value of the area they are a part of is 11 at most?
      - We have made some progress, but this puzzle is definitely tough. There are several ways to go on, though. One of them is to look closely at row 8 and see what you can do by combining all of these small sums.

      This is really a tough one, so feel free to tell me if you still need help after reaching this point, or if my tips were unclear. Good luck!

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    2. Thanks.. I will take a look at it.
      I thougt, I had posted my response wrong yesterday - that's why I posted it again today. Yesterday I managed to find the 9 in region 8 and 1+9 in region 5.

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  7. Hey Bastien
    You're help yesterday was very good... I used the evening to solve the sudoku and at around midnight all the numbers fit in the puzzle..
    Thanks

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    Réponses
    1. Nice! Glad you could make it. I hope you enjoyed the puzzle despite its difficulty; good luck on your next challenge.

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  8. I think I will find something on this page, so maybe I need help some other time...

    *B

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