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 killers too difficult? 
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Posted on: Sun Nov 04, 2012 12:27 am




Posts: 98
Joined: Fri May 13, 2011 12:48 am
Post killers too difficult?
cecileb wrote:
I left the competition long ago, because I got bored solving the easiest puzzles just to add points to my score. I also don't get any thrills tackling the difficult killers. Solving them seems like just an exercise in random guessing (unless I'm missing something & there's some way to better hone my skills). I wouldn't consider leaving the site, because of the many unique types of difficult calcudokus, which are so much fun to solve. I like Patrick's idea of limiting the number of points to acquire each day, rather than decreasing the number of puzzles per day. Btw that new pencil option is wonderful & makes solving many of the puzzles much faster.

Best regards,
cecileb

most puzzle can be solved w/ very little guessing

ack! didn't read it correctly. I was thinking most calkudoku can be solved with very little guessing. As for killers, I tend to agree with you all that it is more of a guessing game than an analytical puzzle.


Last edited by picklepep on Sun Nov 04, 2012 5:19 pm, edited 1 time in total.



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Posted on: Sun Nov 04, 2012 1:07 am




Posts: 116
Joined: Sat May 14, 2011 3:18 am
Post Re: Lowering level of participation
cecileb wrote:
I also don't get any thrills tackling the difficult killers. Solving them seems like just an exercise in random guessing (unless I'm missing something & there's some way to better hone my skills).

I also feel this way about some of the difficult killers... such as two of the ones this past week. I'll have to check to see which dates, but I just couldn't get any traction.

Edit: Went back and found I wasn't able to do the Difficult killer for October 31, and while I managed to solve the one for November 3, it required me to guess between {6,8} and {5,9} for the 14 cage in N5. Fortunately, I picked correctly and didn't have to do major backtracking. What did I miss?? [confused]

picklepep wrote:
most puzzle can be solved w/ very little guessing

I think I've learned most of the tricks (looking for innies and outies, narrowing down possibilities based on large-value 2-cell cages in same row, etc.) but some of them just don't seem to present any footholds. There are too many jagged edges to ever come up with groups of 45.

Is there some website that describes techniques for some of these really difficult ones?


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Posted on: Sun Nov 04, 2012 10:16 pm




Posts: 693
Joined: Fri May 13, 2011 6:51 pm
Post Re: Lowering level of participation
pharosian wrote:
cecileb wrote:
I also don't get any thrills tackling the difficult killers. Solving them seems like just an exercise in random guessing (unless I'm missing something & there's some way to better hone my skills).

I also feel this way about some of the difficult killers... such as two of the ones this past week. I'll have to check to see which dates, but I just couldn't get any traction.

Edit: Went back and found I wasn't able to do the Difficult killer for October 31, and while I managed to solve the one for November 3, it required me to guess between {6,8} and {5,9} for the 14 cage in N5. Fortunately, I picked correctly and didn't have to do major backtracking. What did I miss?? [confused]

picklepep wrote:
most puzzle can be solved w/ very little guessing

I think I've learned most of the tricks (looking for innies and outies, narrowing down possibilities based on large-value 2-cell cages in same row, etc.) but some of them just don't seem to present any footholds. There are too many jagged edges to ever come up with groups of 45.

Is there some website that describes techniques for some of these really difficult ones?


Perhaps you can find interesting the page killersudokuonline.com, in the section “Tips” you can find a few examples of difficult Killers.

I am always inclined to the use of the analysis: when, solving a numerical puzzle, you make a step fully based on analysis you feel sure the backstracking will not occur. As you comment, in the Nov 03 puzzle, you took a lucky “guess”. With the Killer’s it’s generally necessary to prepare some small equations that relate the innies, outies and/or several cells here and there. We also have the interesting restrictions provided by the limited number of combinations for some amounts (and the rule of non-repetition inside a cage); for instance, we know that a cage “12” in two cells is only made by [3,9], [4,8] or [5,7], etc; or “5” and “6”, in the same line, must be [2,3] and [1,5] since a sum of 11, with four numbers, has a unique combination of 1, 2, 3, 5 so the 4 cann’t be present and then 5 must be different than [1,4]; similarly, “14” and “15” in the same line must be [5,9] and [7,8] since a sum of 29, with four numbers, has a unique combination of 5, 7, 8, 9 and the 6 is not present so “14” must be [5,9] and “15” must be [7,8].

I will try to help answering your question on the previous puzzle (the explanations are contained in the graphic itself).

Image

Finally we have arrived to the correct combination for cage “14” = [6,8] in N5 but following an “analytical” process. There are always ways for doing this in every Killer.

The official solution (for future reference to this thread):

Image


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Posted on: Sun Nov 04, 2012 11:11 pm




Posts: 43
Location: Tacoma, WA, USA
Joined: Fri May 13, 2011 4:03 am
Post Re: Lowering level of participation
I disagree with the critiques of the Kindly Sudokus. I think they're tremendously interesting, especially as a little variety from the calcudokus - I wouldn't get rid of them or reduce the number of them at all.

I also don't think they require guessing. I don't always GET all of them, but the ones I do get (most of them) can be done with detective work, without guessing.


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Posted on: Mon Nov 05, 2012 1:42 am




Posts: 116
Joined: Sat May 14, 2011 3:18 am
Post Re: Lowering level of participation
Thank you, clm, for your very helpful explanation. I didn't see that g8 was the "outie" for N7 and N8, and therefore didn't get the 2 in d1 which led to the 6 in e3, which was crucial to making the {6,8} determination for the 14 cage. I will try to look for more opportunities such as that when I get stuck next time.

You rock!!! [thumbsup]

rossiniman wrote:
I disagree with the critiques of the Kindly Sudokus. I think they're tremendously interesting, especially as a little variety from the calcudokus - I wouldn't get rid of them or reduce the number of them at all.

I also don't think they require guessing. I don't always GET all of them, but the ones I do get (most of them) can be done with detective work, without guessing.

I don't mean to sound critical of the K Sudokus... I really love doing them and look forward to them and don't want to see any reduction in them at all. [wub]

But that doesn't mean I love bashing my head against a wall, which is what it feels like sometimes when I just can't figure out how to "analyze" a solution. You say you don't always GET them. Well, with the K Sudokus, I feel that I "should" be able to get them all (unlike the modulo puzzles, for example, which I find too frustrating due to the large number of possibilities for the mod cages). It frustrates the crap out of me when I can't see a way to solve one of these things. [angry]


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Posted on: Mon Nov 05, 2012 5:02 am




Posts: 43
Location: Tacoma, WA, USA
Joined: Fri May 13, 2011 4:03 am
Post Re: killers too difficult?
I have the perfect solution. When I can't get one, and I feel exactly the same way, I figure all it would take is a LITTLE more time. All that's needed to provide that little more time is quitting my job, ignoring my family, and abandoning sleep!


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Posted on: Wed Nov 07, 2012 11:03 pm




Posts: 693
Joined: Fri May 13, 2011 6:51 pm
Post Re: Lowering level of participation
pharosian wrote:
Thank you, clm, for your very helpful explanation. I didn't see that g8 was the "outie" for N7 and N8, and therefore didn't get the 2 in d1 which led to the 6 in e3, which was crucial to making the {6,8} determination for the 14 cage. I will try to look for more opportunities such as that when I get stuck next time.

You rock!!! [thumbsup]
...


Welcome, it’s very amused to talk about these questions.

OK, now that you have probably visited the page killersudokuonline.com, and though the type of puzzle below does not exist in our site, I would like to comment something about it since it can provide some additional practice to the solution of our Killer’s. For this purpose I am sending a separate post to the Section “Solving strategies and tips” (BTW, the calcudokers should be better puzzlers than the killersudokers :-) :-)).

In general, a Killer Sudoku with inequalities (the signs <, >, =, compare the value of the individual cells or cages involved; in the site killersudokuonline.com they name this puzzle Greater Than Killer Sudoku) should be more difficult (requiring more time) than the Standard Killer Sudoku since it contains less information (in this example we have 22 “blind” cages containing 45 numbers while the 17 “normal” cages contain the other 36 numbers):

Image


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Posted on: Wed Dec 19, 2012 9:56 pm




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Joined: Thu May 26, 2011 2:47 am
Post Re: killers too difficult?
I disagree with the sentiment that Killer puzzles are best solved by guessing. I have yet to do that. Instead I will get a few numbers and then look at sum combinations such as for 5 or 6 which are limited and so often decipherable. Once a third is filled in (I highlight combinations that I know must go in a cage but not the order), then the Sudoku part starts to come into play since I can sometimes find which row (or column) in a box must contain a given digit. All in all it makes for a very interesting challenge.


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Posted on: Fri Dec 21, 2012 5:22 am




Posts: 116
Joined: Sat May 14, 2011 3:18 am
Post Re: killers too difficult?
ray wrote:
I disagree with the sentiment that Killer puzzles are best solved by guessing. I have yet to do that. Instead I will get a few numbers and then look at sum combinations such as for 5 or 6 which are limited and so often decipherable. Once a third is filled in (I highlight combinations that I know must go in a cage but not the order), then the Sudoku part starts to come into play since I can sometimes find which row (or column) in a box must contain a given digit. All in all it makes for a very interesting challenge.

Now that I've been doing these for a while and learned some of the tricks, it's rare that I don't complete one--and I don't have to guess. Today's Difficult had me pulling out my hair for a while until I realized that the 2 in N4 could only fit in one of two cells. That led to quite a few more cells being filled in, which eventually enabled me to solve the darn thing. It still required me to track down and eliminate a few paths in N2 and N3 before I finally got it, though. Whew!


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Posted on: Fri Dec 21, 2012 7:07 am




Posts: 193
Joined: Tue May 24, 2011 4:55 pm
Post Re: killers too difficult?
pharosian wrote:
Now that I've been doing these for a while and learned some of the tricks, it's rare that I don't complete one--and I don't have to guess. Today's Difficult had me pulling out my hair for a while until I realized that the 2 in N4 could only fit in one of two cells. That led to quite a few more cells being filled in, which eventually enabled me to solve the darn thing. It still required me to track down and eliminate a few paths in N2 and N3 before I finally got it, though. Whew!

I had a hard time solving today's difficult too, but luckily I also managed without having to go very far in testing unproven assumptions. After taking the step you described I took a closer look at column 4. With 1, 2 and 8 at the left of N5 and a cage with the sum of 17 at the left of N8, the sum of the three numbers at the left of N2 would also have to be 17. And wherever 9 went, 3 and 5 would also have to go, meaning that the numbers in the still-empty part of column 4 where those three numbers didn't go would have to be 4, 6 and 7.

I tried putting 4, 6 and 7 at the leftmost cells of N2 and realised that the cage 17 straddling the top of N1 and N2 would then also have to contain those three exact numbers. Seeing that 6 and 7 were already at the right of N4 (as per your hint), 4 would have to go into the top cell of column 3 and into the bottom left cell of N2. The numbers in the middle and right cells at the bottom of N2 would then have to be 8 and 3 (so that the sum of all the numbers in N2 would be 45), and the sum of the numbers in the two leftmost cells of the 24 cage (those in row 3) must then be 9. But with 2 and 6 already in that row (at the right of N4 as per your hint) and 4 and 8 already used in the part of the 24 cage at the bottom of N2, there was no even number left to use in order to obtain a sum of 9 in the two still-empty cells of cage 24. In conclusion, putting 4, 6 and 7 at the left of N2 led to a contradiction, so they must go to the left of N8 instead while 3, 5 and 9 must go to the left of N2. The puzzle became quite manageable from then on.

Sorry, I just couldn't resist verbalising excessively [smile]


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