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Difficult Killer Sudoku for 16 Sept 2012
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Posted on: Sun Sep 16, 2012 7:17 pm

Posts: 116
Joined: Sat May 14, 2011 3:18 am
Difficult Killer Sudoku for 16 Sept 2012
Hi,

Does anyone who solved today's difficult Killer Sudoku have any tips for solving it? I am nearly always able to solve all three puzzles, but this one has me stumped. I got a couple of cells figured out, but either I'm missing something or this puzzle is FAR more difficult than others with a similar rating.

Did anyone else struggle with this one?

Thanks for any help.

Posted on: Sun Sep 16, 2012 7:24 pm

Posts: 98
Joined: Fri May 13, 2011 12:48 am
Re: Difficult Killer Sudoku for 16 Sept 2012
pharosian wrote:
Hi,

Does anyone who solved today's difficult Killer Sudoku have any tips for solving it? I am nearly always able to solve all three puzzles, but this one has me stumped. I got a couple of cells figured out, but either I'm missing something or this puzzle is FAR more difficult than others with a similar rating.

Did anyone else struggle with this one?

Thanks for any help.

Yeah this one was pretty difficult. Alot of T&E. I think my breakthrough came when I realized that some of the cages were isomorphic(i.e. they must have the same numbers in them no matter which block they are in{I think my language here is bad :)})

Try starting on the right, top than middle

Posted on: Sun Sep 16, 2012 8:01 pm

Posts: 2258
Joined: Thu May 12, 2011 11:58 pm
Re: Difficult Killer Sudoku for 16 Sept 2012
pharosian wrote:
Does anyone who solved today's difficult Killer Sudoku have any tips for solving it? I am nearly always able to solve all three puzzles, but this one has me stumped. I got a couple of cells figured out, but either I'm missing something or this puzzle is FAR more difficult than others with a similar rating.

It's nice to see this confirmed in the new solver: it rates it considerable
harder than that killersudokuonline sample puzzle

Patrick

Posted on: Sun Sep 16, 2012 11:06 pm

Posts: 116
Joined: Sat May 14, 2011 3:18 am
Re: Difficult Killer Sudoku for 16 Sept 2012
Thanks, picklepep!

Posted on: Mon Sep 17, 2012 3:16 am

Posts: 193
Joined: Tue May 24, 2011 4:55 pm
Re: Difficult Killer Sudoku for 16 Sept 2012
I agree: Yesterday's difficult killer sudoku was indeed a killer! Because I had said just the day before that I was able to solve the difficult killer sudokus at calcudoku.org "on-screen, memorizing candidate numbers when necessary and doing the calculations in my head", I felt obliged to try to do so even if it was fiendishly difficult and I ended up using hours

Surprisingly, more than 50 puzzlers have actually managed the 16 Sept difficult killer sudoku so far, which must be a sign that this site is gaining traction with hardcore puzzlers

pnm wrote:
It's nice to see this confirmed in the new solver: it rates it considerable
harder than that killersudokuonline sample puzzle

Hmm, I actually half-suspected you of having cranked up the level just to punish my hubris, going, "I, Min ze Merciless, have forged a most eevil keeller sudoku! Mwahahaha!" in your secret (virtual?) Dutch lair. Today, 17 Sept, the difficult killer sudoku was no more difficult than usual, though. It may actually have been slightly easier.

Posted on: Tue Sep 18, 2012 1:40 pm

Posts: 2258
Joined: Thu May 12, 2011 11:58 pm
Re: Difficult Killer Sudoku for 16 Sept 2012
bram wrote:
Hmm, I actually half-suspected you of having cranked up the level just to punish my hubris, going, "I, Min ze Merciless, have forged a most eevil keeller sudoku! Mwahahaha!" in your secret (virtual?) Dutch lair. Today, 17 Sept, the difficult killer sudoku was no more difficult than usual, though. It may actually have been slightly easier.

Soon the difficulty level should be more consistent (making many improvements to the solver).

And yes, at some point I'll punish people by showing a different puzzle depending on who's logged in:
bram -> Killer Ultra
everybody else -> normal difficult Killer

Posted on: Wed Sep 19, 2012 3:56 am

Posts: 193
Joined: Tue May 24, 2011 4:55 pm
Re: Difficult Killer Sudoku for 16 Sept 2012
pnm wrote:
And yes, at some point I'll punish people by showing a different puzzle depending on who's logged in:
bram -> Killer Ultra
everybody else -> normal difficult Killer

Wow, you surely wasted no time in implementing that bit! I only managed today's Dee-Kay because I tested a wild assumption that yielded such a promising-looking set of constraints that I figured it was probably "to good to be true". However, I didn't run into any contradictions and soon the puzzle was solved. (Hint for other solvers who got stuck solving the 19 Sept difficult killer: In the top middle 3x3 section, I had found that 8 and 9 go into the two cells of the "23" cage that are in that section. Then I noticed that if 7 does not go into the "18" cage, then 3, 4, 5 and 6 go into that cage while 1, 2 and 7 go into the three remaining cells in the section.)

pnm wrote:
Soon the difficulty level should be more consistent (making many improvements to the solver).

Yes, a rating of 176 is quite realistic, indicating that this is indeed a bad-ass puzzle

Posted on: Wed Sep 19, 2012 5:19 pm

Posts: 116
Joined: Sat May 14, 2011 3:18 am
Re: Difficult Killer Sudoku for 16 Sept 2012
bram wrote:
I only managed today's Dee-Kay because I tested a wild assumption that yielded such a promising-looking set of constraints that I figured it was probably "to good to be true". However, I didn't run into any contradictions and soon the puzzle was solved. (Hint for other solvers who got stuck solving the 19 Sept difficult killer: In the top middle 3x3 section, I had found that 8 and 9 go into the two cells of the "23" cage that are in that section. Then I noticed that if 7 does not go into the "18" cage, then 3, 4, 5 and 6 go into that cage while 1, 2 and 7 go into the three remaining cells in the section.)

Wow, that was incredibly helpful! Thanks!

I'd already got the 8 and 9 in the 23 cage and knew the other three corners had a sum of 10, but after that I was stuck, even knowing a fair bit about the left 3 columns of the puzzle. With what I already had, your clue gave me the "leg up" I needed to get the rest of the way.

Posted on: Thu Sep 20, 2012 1:26 am

Posts: 193
Joined: Tue May 24, 2011 4:55 pm
Re: Difficult Killer Sudoku for 16 Sept 2012
pharosian wrote:
Wow, that was incredibly helpful! Thanks!

I'd already got the 8 and 9 in the 23 cage and knew the other three corners had a sum of 10, but after that I was stuck, even knowing a fair bit about the left 3 columns of the puzzle. With what I already had, your clue gave me the "leg up" I needed to get the rest of the way.

You're very welcome. I'm a great fan of clm's impressive contributions to the solving strategies and tips section and tried to do something similar to this recent clue for a harder-than-difficult killer sudoku at another site. Nice to know it was useful.

Posted on: Thu Sep 20, 2012 4:14 pm

Posts: 2258
Joined: Thu May 12, 2011 11:58 pm
Re: Difficult Killer Sudoku for 16 Sept 2012
pnm wrote:
Soon the difficulty level should be more consistent (making many improvements to the solver).

More improvements to the solver, and the rating of killer sudokus
(it solves an "outrageous" puzzle on the killersudokuonline site in about a second now).

So now I know which of the upcoming difficult puzzles will be harder than usual:
- Sunday Sep 23
- Tuesday Sep 25 (but not as bad as Sep 23, 19, and 16)(comparable to the ones on Sep 1 and Sep 5)
- Sunday Sep 30

So you've been warned

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