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today's 7x7
http://www.calcudoku.org/forum/viewtopic.php?f=16&t=1004
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Author:  beaker  [ Thu Dec 07, 2017 4:03 am ]
Post subject:  today's 7x7

Today's 7x7 I found was one of the toughest (maybe because I have 2 grandchildren upstairs) but still, I just couldn't find the proper combination for the 3 celled cage valued at -3......any one else with same problem [huh]

Author:  paulv66  [ Thu Dec 07, 2017 12:02 pm ]
Post subject:  Re: today's 7x7

beaker wrote:
Today's 7x7 I found was one of the toughest (maybe because I have 2 grandchildren upstairs) but still, I just couldn't find the proper combination for the 3 celled cage valued at -3......any one else with same problem [huh]


I always find puzzles with negative numbers difficult. I think it's just the metal gear shift that's required, particularly where the operator is minus. I find the best way to approach them is to try to find where the zeroes are positioned and I bold the zero cells.

Today's puzzle took me a bit longer than usual (time showed for completing it was 27 minutes, but I had a conversation in the middle of doing it, so actual puzzle time was probably around 15 minutes). But I wouldn't say I found it unusually difficult.

Author:  pnm  [ Thu Dec 07, 2017 12:16 pm ]
Post subject:  Re: today's 7x7

For (later) reference, this is the puzzle:

Image

Author:  paulv66  [ Thu Dec 07, 2017 12:19 pm ]
Post subject:  Re: today's 7x7

pnm wrote:
For (later) reference, this is the puzzle:

Image


Patrick, that's yesterday's difficult 7x7. I think beaker was referring to today's extra puzzle, which uses numbers from -3 to +3.

Author:  jpoos  [ Thu Dec 07, 2017 2:22 pm ]
Post subject:  Re: today's 7x7

Just finished it in 3 minutes, though I must say I saw some pretty nifty implications just about right of the bat. Will elaborate tomorrow.

beaker wrote:
I just couldn't find the proper combination for the 3 celled cage valued at -3......any one else with same problem [huh]


That cage was one of the last ones I filled in, at which point I didn't really have to use the relation of the cage anymore.

Author:  eclipsegirl  [ Thu Dec 07, 2017 8:06 pm ]
Post subject:  Re: today's 7x7

I was able to work through it without giving it a second thought. When I came in filling possibilities for that cage, I had worked through much of the puzzle so the possibilities were limited. I assume that helped me out.

Author:  jpoos  [ Sat Dec 09, 2017 5:55 pm ]
Post subject:  Re: today's 7x7

As promised, a little elaboration on the solve:

First, the easy stuff:

Image


Now here comes the nifty bit: For the 0+ cage on [b4,c4], there are only 2 ways to fill it in, b4=1 and c4=-1, or b4=3 and c4=-3.
But if we look at column c now, we see that the -3x cage, in combination with cell c4, leaves us with no option but [-2, 1] in the -1+ cage on the bottom (the -3x must contain either a -3 or a -1, which means both -3 and -1 can't be in that -1+ cage).

Image


From here on out it shouldn't be too complicated anymore: you could work your way to something like this:

Image


This gives 0 in e7, and the rest should be fairly trivial.

Author:  beaker  [ Thu Dec 14, 2017 5:38 am ]
Post subject:  Re: today's 7x7

How about today's (Oct. 13 on Pacific West Coast of N.A.)......my "love/hate" relationship with these 7x7's is still on going and today's was again tough for me......the last 2 for some reason has taken me longer to solve ( we still have our grandsons and parents with us as their house interior is being totally re-painted.....so, I guess that might be the reason) but I still had trouble with 2 cages (lower left corner and the -5)....once they were solved the rest was obvious [smile]

Author:  eclipsegirl  [ Thu Dec 14, 2017 5:26 pm ]
Post subject:  Re: today's 7x7

I am going to say you have been distracted with the guests, the Holiday season, and home renovations.

Again, didn't to the 5 - cage til the end.

Author:  beaker  [ Thu Dec 14, 2017 7:05 pm ]
Post subject:  Re: today's 7x7

Eclipsegirl: I usually start with the zeros and then look for the 1 or 2 cages that seem to have a number of possibilities so I guess I'll try the obvious ones first and leave (like you said) the others to the end.......and also......wish you and your family a Merry Christmas.

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