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SM 2020 (Math) Author
Posts: 419
Location: India | Parallel Universe II ---That was a lovely set of puzzles.This being an open forum I will cut myself short right there.
Moving on,here are 2 puzzle genres that are present in the ongoing GP Puzzle round 4.The Prime place puzzle was something where initially I wasn't too flustered with the rules,but after seeing the queries asked in the forum of World puzzle org regarding this(and there seems to be so many) ,I am sure there won't be any who is more confused with the rules now than myself.The first is a prime place puzzle and the second is a Japanese loop puzzle where I am unable to make a start (both taken from the blog maybe puzzles).So dear LMIans, if someone has a very good idea or strategy to tackle these puzzles kindly post here.
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2021 World Sudoku+Puzzle Convention Organizer
Posts: 1809
 
Location: India | I tried that Prime Place and broke it, so maybe I'm misunderstanding the rules. I just thought the converse part of it applies too.. I guess it does. Maybe I went wrong somewhere. But remember that by the rules, since all diagonal lines are given, all isolated cells must contain a diagonal line in the direction of their isolation (e.g. the one non-parallel line is in what I'd call an isolated cell in the direction of that line) in order to contain prime digits. |
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Typed Logic Author
Posts: 241
Location: Indonesia | Prime Place is inherently tough. It has quite a lot of rules (I see you forgot about "connected horizontal/vertical lines must sum to a prime", which immediately deduces R1C3, R3C1, R3C5, R5C3 as primes), and a lot of bruteforcing (for example, a nonprime and a nonprime that sums to a nonprime must be both 4s like R4C1 and R5C2; also when you've identified that R1C3, R2C2, R3C1 are prime, nonprime, prime in that order, and they sum up to a prime, by bruteforce you can find that R2C2 is 1 and R1C3 and R3C1 are equal). I find a rather nice path without too much bruteforcing, which resorts to counting the 3s. Those should be sufficient hints for now? |
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PR 2020 (Shading and Loops) Author
Posts: 668
Location: India | for japanese loop i can see the start at 7 7 7.
as each needs to be two cells. there is only one way to do
then it should be good to go. :) |
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SM 2020 (Math) Author
Posts: 419
Location: India | Invariably the following sequence happens when I see a Nurikabe puzzle in a test and it is becoming more of a nuisance to me :
1)The puzzle is attempted.
2)A lot of time is spent(wasted) on the puzzle .
3)The puzzle is left incomplete .............
This is one of the toughest puzzle genres that I have seen .The puzzle below looks very cruel and I am hopelessly lost in it.I tried to see if only certain numbers can reach some spots to avoid 2X2 oceans.There is nothing of that sort here.The shaded cell connectivity rule is also not of much help.A shaded cell maybe at R3C5 using the above rule?!Not too sure on that.So what is the approach to be used to complete this puzzle and in general what line of thinking is to be adopted while solving a Nurikabe puzzle where in most cases no logical deduction looks immediately apparent?
Edited by kishy72 2014-05-18 10:53 PM
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PR 2020 (MII and Regions) Author
Posts: 55
Location: India | As u Kishy72 R3C5 wil be a shaded cell... if not how wil the shaded cell at R3C6 wil join the other shaded cells.. no way for it to join other... Other thing is R1C1 and R2C1 wil be shaded as not island can go to it... Aftr which R3C2 will be a part of the island 3 or else it wil form a 2*2 shaded square. and after R3C1 wil be shaded or else the shaded part above it wil be blocked.... U can try aftr tht... if at all u r stuck u can still post.. :P |
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SM 2020 (Math) Author
Posts: 419
Location: India | 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.
Edited by kishy72 2015-08-16 12:29 AM
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PR 2020 (Shading and Loops) Author
Posts: 668
Location: India | 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 :)
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SM 2020 (Math) Author
Posts: 419
Location: India | 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! |
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2021 World Sudoku+Puzzle Convention Organizer
Posts: 1809
Location: India | 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. |
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Posts: 102
Location: United States | 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
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SM 2020 (Math) Author
Posts: 419
Location: India | 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. |
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Posts: 102
Location: United States | 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?
Edited by ghirsch 2015-08-17 1:49 AM
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Mean Minis (2020) Author
Posts: 774
Location: India | The top left corner cell has to be a star. |
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2021 World Sudoku+Puzzle Convention Organizer
Posts: 1809
Location: India | 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. |
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WSPC Organizer
Posts: 739
Location: India | @ghirsch
How did you mark the bottom 3-polyomino?
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Posts: 102
Location: United States | 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. |
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SM 2020 (Math) Author
Posts: 419
Location: India | 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. |
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Posts: 102
Location: United States | Thanks everyone, I figured out the rest of it now. |
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SM 2020 (Math) Author
Posts: 419
Location: India | 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.
Edited by kishy72 2015-08-20 7:34 PM
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Posts: 102
Location: United States | A few starting thoughts (though no major break-ins):
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
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SM 2020 (Math) Author
Posts: 419
Location: India | 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? |
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PR 2020 (Shading and Loops) Author
Posts: 668
Location: India | 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=... |
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2021 World Sudoku+Puzzle Convention Organizer
Posts: 1809
Location: India | 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. |
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SM 2020 (Math) Author
Posts: 419
Location: India | Thanks Swaroop and Prasanna ! I could proceed till here after which it's too difficult .Where am I missing the trick?
Edited by kishy72 2015-08-22 12:11 AM
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