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Puzzle Solving Techniques
   LMI Essentials -> Solving Techniques74 posts • Page 2 of 3 • 1 2 3
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-16 12:28 AM (#19049 - in reply to #1525) (#19049) Top




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So, I was solving some Slitherlink puzzles in the hope to get in some kind of 'shape' before Puzzle Ramayan.The following is taken from Round 2 of Puzzle GP(Slovak Round).This themed slitherlink based on 1 had me clueless for a long time.After having tried several uncharted paths which got me nowhere , I tried using intuition (if I may be allowed to call what I implemented that way) : a concept which continues to baffle me and makes me wonder how people use it successfully and if it would ever help in my case , I lost hope on my futile attempts and decided to seek help here.So, if someone can show me light that would help me go until the very end,I will be thankful.

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Edited by kishy72 2015-08-16 12:29 AM
swaroop2011
Subject: Re: Puzzle Solving Techniques @ 2015-08-16 6:33 AM (#19050 - in reply to #1525) (#19050) Top


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Hi kishore that one even i got stuck but not at this point, I do got little progress. So I can at least tell you till that point. Bit difficult to explain but will try to keep it simple.
Notation: 9 rows and 9 columns for dots and 8 rows and 8 columns for clues. I will specify if it indicates clue and rest all will be for dots.

1) There will be line from r6c1 to r7c1 and to similar logic there will be line from r9c3 to r9c4.
2) So above step gives crosses at r5c1 to r5c2 and r5c2 to r5c3, r4c2 to r5c2 and r5c2 to r6c2.
3) Also there are crosses at r8c6 to r9c6, r4c8 to r4c9 , r3c8 to r3c9, r2c8 to r2c9, r1c8 to r2c8, r1c7 to r2c7
4) Now there will be line either from r4c2 to r4c4 or r3c3 to r5c3 to satisfy the r4c2 clue. So that gives crosses at r4c4 to r5c4 and r5c3 to r5c4.
5) Similar logic for clue at r7c2, there will be crosses r6c3 to r6c4 and r6c4 to r7c4.
6) This immediately gives crosses at, r5c4 to r6c4, r5c4 to r5c5 and r6c4 to r6c5.
7) So that gives line from r3c3 to r6c3. Also a line from r7c2 to r7c3.

Hope this helps and takes you few steps further.
If anyone has better start or logic please do let us know :)
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-16 2:56 PM (#19051 - in reply to #19050) (#19051) Top




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Thanks Swaroop for explaining painstakingly and with full lucidity.These helped me a lot and I could complete the puzzle.But sadly,I could not use much of logic even after this which has to do with my own deficiency and completed it after one of my guess paths turned out to be lucky. Thanks again!
prasanna16391
Subject: Re: Puzzle Solving Techniques @ 2015-08-16 3:49 PM (#19052 - in reply to #19051) (#19052) Top


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kishy72 - 2015-08-16 2:56 PM

Thanks Swaroop for explaining painstakingly and with full lucidity.These helped me a lot and I could complete the puzzle.But sadly,I could not use much of logic even after this which has to do with my own deficiency and completed it after one of my guess paths turned out to be lucky. Thanks again!


I remember that I guessed on this Slitherlink in competition and couldn't find a path later beyond a certain point either.
ghirsch
Subject: Re: Puzzle Solving Techniques @ 2015-08-16 11:58 PM (#19057 - in reply to #1525) (#19057) Top




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Could anyone give me some tips for how to approach the Fillomino Stars from the IPC last week? I found the threes in the top-left corner and the two stars in the third column, but I couldn't find anything else to do.

(Also, how do you attach a picture to a forum post here? I could upload the grid with what I have done so far.)

Edited by ghirsch 2015-08-17 12:00 AM
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 12:42 AM (#19058 - in reply to #19057) (#19058) Top




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ghirsch - 2015-08-16 11:58 PM

(Also, how do you attach a picture to a forum post here? I could upload the grid with what I have done so far.)


http://tinypic.com/.

Upload your image.Paste the link containing the HTML version of the image here.
ghirsch
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 1:46 AM (#19059 - in reply to #19058) (#19059) Top




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Thanks kishy.

This is all I could come up with for the Fillomino Stars puzzle from the IPC last week (the x's are stars). Can anyone provide some tips for where to go from here?
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Edited by ghirsch 2015-08-17 1:49 AM
rakesh_rai
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 5:57 AM (#19060 - in reply to #1525) (#19060) Top



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The top left corner cell has to be a star.
prasanna16391
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 6:06 AM (#19061 - in reply to #1525) (#19061) Top


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Have a marking - dot, or a small x in the corner or whatever suits you best - to denote when a cell cannot be a star, even though you don't know the region filling it. This will help. Key will be seeing R4C1 and R5C2 cannot be stars using hidden polyomino extension for contradictions.
vopani
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 9:41 AM (#19063 - in reply to #1525) (#19063) Top


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@ghirsch
How did you mark the bottom 3-polyomino?
ghirsch
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 11:14 AM (#19064 - in reply to #19063) (#19064) Top




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rakesh_rai - 2015-08-16 6:57 AM

The top left corner cell has to be a star.


Why can't it be a 1?

Rohan Rao - 2015-08-16 10:41 AM

@ghirsch
How did you mark the bottom 3-polyomino?


You're right, it could be a star.

prasanna16391 - 2015-08-16 7:06 AM

Have a marking - dot, or a small x in the corner or whatever suits you best - to denote when a cell cannot be a star, even though you don't know the region filling it. This will help. Key will be seeing R4C1 and R5C2 cannot be stars using hidden polyomino extension for contradictions.


I'll give that sort of notation a try, thanks for the advice and starting point.
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 11:48 AM (#19065 - in reply to #19064) (#19065) Top




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ghirsch - 2015-08-17 11:14 AM

rakesh_rai - 2015-08-16 6:57 AM

The top left corner cell has to be a star.


Why can't it be a 1?

The reasoning goes this way :

i)R1 and R2 contain a total of 4 stars.
ii)Each 2X2 square can contain only a maximum of 1 star.Therefore cells R1C9,R1C10,R2C9 and R2C10 can contain a maximum of one star.Similarly Cells R1C6,R1C7,R2C6 and R2C7 can have a maximum of 1 star.
iii)To make the total 4 stars,the only place is R1C1.It has to be a star.
ghirsch
Subject: Re: Puzzle Solving Techniques @ 2015-08-17 7:21 PM (#19066 - in reply to #1525) (#19066) Top




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Thanks everyone, I figured out the rest of it now.
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-20 7:34 PM (#19102 - in reply to #19066) (#19102) Top




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A NEWS Puzzle from forsmarts which I have no clue on how to go about.There is no particular reason for posting this puzzle now .I found it lying in a corner of my room along with many other unsolved puzzles.While I could do some of the rest,this caused me trouble .I had a look at the solution and still could not figure out the start.So if someone can share the starting steps ,it would be helpful.

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Edited by kishy72 2015-08-20 7:34 PM
ghirsch
Subject: Re: Puzzle Solving Techniques @ 2015-08-20 11:10 PM (#19103 - in reply to #1525) (#19103) Top




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A few starting thoughts (though no major break-ins):

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1) You can eliminate some spaces (the red slashes) because of the existing directions in regions (e.g. R1C6 is north of the N in the region).
2) You can eliminate some spaces (the green slashes) because the only possible entry is already in that row/column (e.g. R1C3 is northwest of the S, but the column already has an N and a W).
3) There are 22 regions (so 44 letters) and 12 rows/columns. Each type of letter can only go in 11 different rows/columns (e.g. there can't be an S in the top column), so every letter must be in 11 of 12 rows/columns.
4) This isn't included in the picture, but the region containing R5C7 can't have an N or S in it, so there must be a W in R5C7 (I'm sure this can be used elsewhere too).

Edited by ghirsch 2015-08-20 11:31 PM
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-21 12:17 AM (#19104 - in reply to #19103) (#19104) Top




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Hi ghirsch. Thanks a lot for the starters.However,I am still not clear.How did you shade R2C5/C6/C7 and lots of other squares too.For instance ,why can't be a E present in R2C5 (East of South) and a W present in R1C6 and R2C6/7 (West of North)

The region containing W(R9C3) has E in R12C5 as per solution.How is it even possible?? E has to be right opposite W right?I mean in line with W.How's it located to the lower right of it or in words South East of it?
swaroop2011
Subject: Re: Puzzle Solving Techniques @ 2015-08-21 3:27 AM (#19105 - in reply to #19104) (#19105) Top


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kishy72 - 2015-08-21 12:17 AM

Hi ghirsch. Thanks a lot for the starters.However,I am still not clear.How did you shade R2C5/C6/C7 and lots of other squares too.For instance ,why can't be a E present in R2C5 (East of South) and a W present in R1C6 and R2C6/7 (West of North)

The region containing W(R9C3) has E in R12C5 as per solution.How is it even possible?? E has to be right opposite W right?I mean in line with W.How's it located to the lower right of it or in words South East of it?


Hi Kishy & ghirsch,
I believe you have not interpreted rules correctly.
The alphabets has to just follow the sense of direction.
What I meant by this is, E just has to be on right hand side of W, it doesn't need to be in line with W. it can be up or down but right side.
E.g. Consider the region R8C5 "W" clue region. E can be in R8C6, R7C6 or R9C6 but it cannot be at R12C5.

Similarly for N, W , S as well.
Another example S has to be on right side and at same time downside of W.

Check this given example for clarity:
http://logicmastersindia.com/lmitests/dl.asp?attachmentid=147&view=...
prasanna16391
Subject: Re: Puzzle Solving Techniques @ 2015-08-21 8:20 AM (#19107 - in reply to #19104) (#19107) Top


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kishy72 - 2015-08-21 12:17 AM

Hi ghirsch. Thanks a lot for the starters.However,I am still not clear.How did you shade R2C5/C6/C7 and lots of other squares too.For instance ,why can't be a E present in R2C5 (East of South)


Because then S won't be South of E. Look at it both ways, simply.
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-22 12:07 AM (#19118 - in reply to #19107) (#19118) Top




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Thanks Swaroop and Prasanna ! I could proceed till here after which it's too difficult .Where am I missing the trick?

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Edited by kishy72 2015-08-22 12:11 AM
rob
Subject: Re: Puzzle Solving Techniques @ 2015-08-22 2:06 AM (#19119 - in reply to #1525) (#19119) Top


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The upside down L tetromino must have an N in the top row. Then you get an NW-pair in row 3.
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-22 3:02 AM (#19120 - in reply to #19119) (#19120) Top




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rob - 2015-08-22 2:06 AM

The upside down L tetromino must have an N in the top row. Then you get an NW-pair in row 3.


I don't see how the former leads to the latter?! Where is the NW pair that you refer in row 3?How did you deduce that?
swaroop2011
Subject: Re: Puzzle Solving Techniques @ 2015-08-22 10:56 PM (#19134 - in reply to #1525) (#19134) Top


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Hi kishy,
I haven't solved completely but looking at your image, I can tell you next few steps immediately:
1) R5C9 and R5C10 --> N will come in that region no matter what and in one of these places. (you can see what happens if N will not come)
2) Because of this R5C12 will be cross.
3) Now this gives N-W pair in Row 3, N or W at R3 -C5C6 AND N OR W at R3 C11-12.
4) So this eliminates N at R3 C1C2.
5) So this gives "S" at R5C1 and "E" at R3C2. So that will give "S" at r8c3.
I believe it should go easy after this.

kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-22 11:38 PM (#19135 - in reply to #19134) (#19135) Top




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I can't thank you enough Swaroop.I have done and dusted the puzzle finally and that's a tremendous relief after breaking my head for close to 2 days.The way you explained about that NW Pair in point 3 made me see clearly what I failed to observe....
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-30 2:49 PM (#19202 - in reply to #1525) (#19202) Top




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A Numberlink puzzle.I realized that this puzzle has many ways of completing itself.Where am I going wrong?
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Edited by kishy72 2015-08-30 2:50 PM
kishy72
Subject: Re: Puzzle Solving Techniques @ 2015-08-30 2:52 PM (#19203 - in reply to #19202) (#19203) Top




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In addition,in the above puzzle,I had to use the constraint that all cells need to be visited by paths without which I found 'n' number of ways of completing this puzzle.Is there something critical that I am missing here?
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