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stuck in this sudoku
   LMI Essentials -> Solving Techniques159 posts • Page 1 of 7 • 1 2 3 4 5 6 7
prasanna16391
Subject: Re: stuck in this sudoku @ 2012-09-22 12:14 PM (#8622 - in reply to #8621) (#8622) Top


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kishy72 - 2012-09-22 11:44 AM

Administrator - 2012-09-21 9:51 PM

Focus on R7C2 and R9C2 and column 2. You should be able find the next steps.

Spoiler: show
Given that you have already marked R2C2 and R8C2 as 78, R7C2 and R9C2 have naked pair 36. So R5C3 is 6 and R5C2 is 9.


hi i m not getting it.How did u lock (3/6)in (R7C2 /R9C2).(3 and 6) eliminated from R2C2,R3C2,R4C2-perfectly ok.But only 3 is getting eliminated from R5C2 .So 6 might be present in R5C2 right?!correct me if i am missing something.


In the bottom left box, the only digits that can be there are 3,6,7,8 right? Now in C2, you already have a place in R2 for 7-8, and R8 for 7-8. So 7-8 can't be in any of the rest of the cells in C2. So, R7 and R9 of C2 cannot have 7-8, and the only remaining digits that are possible from the original 4 is 3 and 6.
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-22 1:44 PM (#8625 - in reply to #8622) (#8625) Top


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So basically R9C3 contains either 7 or 8 and therefore......................clear now . will be posting many more stuck sudokus .Thanks guys!
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-23 8:09 PM (#8642 - in reply to #8611) (#8642) Top


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second in the list of sudokus ....where i m unable to cross beyond this point ...fatigue sets in after a certain point...not able to lock any number after this ....

Administrator
Subject: Re: stuck in this sudoku @ 2012-09-23 8:28 PM (#8643 - in reply to #8611) (#8643) Top


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Where do you put 2 in column 3?

Spoiler: show
Given that you have already marked triplets 2/3/4 in row 3 (C5,C8,C9), R3C3 can not be 2


It should solve pretty smoothly after that.
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-23 9:33 PM (#8644 - in reply to #8643) (#8644) Top


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Administrator - 2012-09-23 8:28 PM

Where do you put 2 in column 3?

Spoiler: show
Given that you have already marked triplets 2/3/4 in row 3 (C5,C8,C9), R3C3 can not be 2


It should solve pretty smoothly after that.

Beautiful!i completed very fast after putting that number...great spotting!...hope i remember these small intricacies and implement them in future sudokus.thnk u !
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-25 4:15 PM (#8660 - in reply to #8611) (#8660) Top


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third in the series of stuck sudokus...
how do i proceed from here fellas?!

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prasanna16391
Subject: Re: stuck in this sudoku @ 2012-09-25 4:59 PM (#8661 - in reply to #8611) (#8661) Top


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R1C6 can only be 5-7 due to normal single eliminations of 3,6,2. Similarly, R1C5 can only be 2-5-7. As you have already marked R1C9 as 5-2, that makes a triplet meaning 7 can only be in R1C5/6. It can also only be in R5C5/6, as you have marked. So in C4, you get just one spot to place the 7.
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-25 7:49 PM (#8662 - in reply to #8661) (#8662) Top


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prasanna16391 - 2012-09-25 4:59 PM

R1C6 can only be 5-7 due to normal single eliminations of 3,6,2. Similarly, R1C5 can only be 2-5-7. As you have already marked R1C9 as 5-2, that makes a triplet meaning 7 can only be in R1C5/6. It can also only be in R5C5/6, as you have marked. So in C4, you get just one spot to place the 7.


amazing ..and here was i under the false assumption all these years that all it takes to solve a sudoku is a set of simple rules and logic when the tricks to be learnt in the trade is endless....i know i certainly wouldn't have placed that 7 after making that deduction of locking it in R1C5/R1C6....i m learning new tricks in sudoku ....all the 3 sudokus i failed to solve has some triplets...!!!!!i feel i m improving gradually after joining LMI....thnks prasanna!

Edited by kishy72 2012-09-25 7:50 PM
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-27 11:05 PM (#8673 - in reply to #8611) (#8673) Top


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4th in the series ..help me out on this one fellas....hope u guys are not too busy in prep for wc...i am sure i combed the entire sudoku for triplets and could not notice anyImage and video hosting by TinyPic

Edited by kishy72 2012-09-27 11:05 PM
prasanna16391
Subject: Re: stuck in this sudoku @ 2012-09-27 11:34 PM (#8674 - in reply to #8611) (#8674) Top


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I remember how I solved this one(thats a rarity, I generally struggle to re-solve things).

Anyway, see R2 and R8. whichever way you see it, R2/8C6 has to be 1/3. Should be simple to see, say 1 and 3 are in R2C4 and C5, then both have to be in R8C6, and vice versa. So R7C6 has to be 6.
akash.doulani
Subject: Re: stuck in this sudoku @ 2012-09-28 12:34 PM (#8681 - in reply to #8611) (#8681) Top


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there is a triplet of 458 in r1r3r5/c6. after that u get a 6 in r7c6. its plain solving after that
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-28 1:02 PM (#8683 - in reply to #8681) (#8683) Top


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akash.doulani - 2012-09-28 12:34 PM

there is a triplet of 458 in r1r3r5/c6. after that u get a 6 in r7c6. its plain solving after that


Yes indeed. I could not spot that...
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-28 1:11 PM (#8684 - in reply to #8611) (#8684) Top


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A general query guys....is it advisable to put more than 2 possible numbers in a box? Initially i was not in the habit of putting possible numbers in a box.In fact i hated that since i felt it made the whole sudoku very clustered.But i have realised that it is impossible to solve sudokus of greater difficulty without making a note of the possible numbers that occur in a box.But still is it advisable to write 3-4 numbers in a box and try to solve it if u get stuck, or to just write numbers where you get only 2 after eliminating the rest..This is something which i had always wanted to know from others because even after putting 2, i have got stuck in many a sudoku and the whole thing gets clear only when i put 3 numbers ...want to be sure that sudokus can be solved without writing more than 2 possible numbers in the box....ideas are welcome...
prasanna16391
Subject: Re: stuck in this sudoku @ 2012-09-28 3:57 PM (#8687 - in reply to #8611) (#8687) Top


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Its about the method that suits you best. Personally, I don't like using pencil marks at all. I do better on sites without pencil marks, and I try but I can't stop myself from using them subconsciously when they are there as a part of the interface(been trying to). I've talked to others though and the normal thing is to note down numbers to keep track. So I suppose you'll find this way easier. The difficult ones need a lot of pencil marks, because to add difficult tricks, the creator would have to use a larger group of numbers in the grid and solving them requires an understanding of that entire group. So there's nothing wrong in entering 4-5 pencil marks in a cell as long as you don't end up confusing yourself(which is my problem and why I'm faster without that).

Edited by prasanna16391 2012-09-28 3:58 PM
akash.doulani
Subject: Re: stuck in this sudoku @ 2012-09-28 9:38 PM (#8689 - in reply to #8611) (#8689) Top


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@ kishore : from where do you get those sudokus ? they are pretty interesting to solve. can you share the source ?
kishy72
Subject: Re: stuck in this sudoku @ 2012-09-28 10:56 PM (#8690 - in reply to #8689) (#8690) Top


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I take them from fed sudoku...choose puzzle blogs from LMI home screen -->Fedsudoku--->sudoku archive--->classic printable....
They are my daily dosage of tablets for improving sudoku skills.
prasanna16391
Subject: Re: stuck in this sudoku @ 2012-09-28 11:32 PM (#8691 - in reply to #8690) (#8691) Top


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kishy72 - 2012-09-28 10:56 PM

I take them from fed sudoku...choose puzzle blogs from LMI home screen -->Fedsudoku--->sudoku archive--->classic printable....
They are my daily dosage of tablets for improving sudoku skills.


Akash is a regular there, he's just not been able to do them lately so didn't know I suppose. Anyway, I'm a regular there too. There's other sites as well with daily sudokus like Sudokucup, mindoku. These 3 are my daily routine anyway. Related to your earlier pencil marks question, mindoku's interface doesn't have pencil marks.
kishy72
Subject: Re: stuck in this sudoku @ 2012-10-06 9:51 PM (#8735 - in reply to #8691) (#8735) Top


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the way please in this
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Edited by kishy72 2012-10-06 9:57 PM
kishy72
Subject: Re: stuck in this sudoku @ 2012-10-06 9:53 PM (#8736 - in reply to #8735) (#8736) Top


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oh my !!!!
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Subject: Re: stuck in this sudoku @ 2012-10-08 8:52 PM (#8739 - in reply to #8736) (#8739) Top


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Just by going the marks you have done (and assuming that they are correct), where do you put 3 in Box2?

However, I think you have gone wrong somewhere. I couldn't resolve the bottom 3 rows so early in the solve.
kishy72
Subject: Re: stuck in this sudoku @ 2012-10-08 9:31 PM (#8740 - in reply to #8611) (#8740) Top


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i have addled the sudoku so much that i could not see that direct spotting...and yes i have gone wrong. I started from the beginning again and i saw where i went wrong ....Thnks deb!
kishy72
Subject: Re: stuck in this sudoku @ 2012-10-22 7:42 PM (#8783 - in reply to #8740) (#8783) Top


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So fellas another of those tough computer generated ones where i feel it has managed to give the bare minimum number of numbers required .... a tough nut to crack for me....tried for 28mins.....totally warped .....shw me the way Lmians!!

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Edited by kishy72 2012-10-22 7:42 PM
kishy72
Subject: Re: stuck in this sudoku @ 2012-10-22 9:20 PM (#8786 - in reply to #8783) (#8786) Top


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and if possible post a link where i can see these versions guys
Untouchable sudoku,Disjoint groups ,Symetric unequal , Antiknight
Queens ,Quadro ,Touchy , DuoDoku.... not even heard of some of these variants...planning to take part in sudoku cup want to try atleast one of each of these versions(hopefully) before the test.
prasanna16391
Subject: Re: stuck in this sudoku @ 2012-10-23 1:02 AM (#8787 - in reply to #8786) (#8787) Top


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Firstly the Classic - I remember this one. What I did while solving was focus in the first box. By process of elimination, you get that R2C1, R2C3 can only contain either of 4-6-9. You've already marked R2C7 containing 4-6. This makes a triplet and eliminates 6 from the 2-6 in R2C5, so you have a 2 there. Should be ok after that.

For the variants - You can look at past Monthly tests for some. I think I remember off the top of my head an Anti Knight in Sudoclones and a Queen Sudoku in Diagonal Vision. Apart from that, you have Disjoint groups in the Fed Sudoku site itself, in the Alternatives section. So too Quadro I think. There's also this site(Where disjoint groups is called Offset, Symmetric Unequal is I think No Mirror).

Edited by prasanna16391 2012-10-23 1:05 AM
Fred76
Subject: Re: stuck in this sudoku @ 2012-10-23 2:00 AM (#8788 - in reply to #8786) (#8788) Top



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kishy72 - 2012-10-22 9:20 PM

and if possible post a link where i can see these versions guys
Untouchable sudoku,Disjoint groups ,Symetric unequal , Antiknight
Queens ,Quadro ,Touchy , DuoDoku.... not even heard of some of these variants...planning to take part in sudoku cup want to try atleast one of each of these versions(hopefully) before the test.


You can also find some of them in the monthly test authored by Jan Mrozowski 2 years ago, called "Classic Look-Alikes", it's basically the same concept as the 1st round of sudokucup:

http://logicmastersindia.com/lmitests/?test=M201007S

Fred
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