About R9C8 at that point in the puzzle. The 9th row needed 2, 5 & 9. However the R9C8 cell is forced to have written 8 because of the 5 in the little box along with the 9 pencil marks.
Thanks Mark. I slogged my way thru to the Y-wing point at 13:45 of the video and then got very stuck. Once the Y-Wing was used to eliminate the 8 at R1 C9, then the puzzle just unravelled quickly. Your video has made it much easier for me to learn how to spot and use Y-wings. Cheers
At 9.07, there can only be an 8 whereas you say it must be an 8-9 pair. A 9 cannot go there. After that I believe your analysis of the next 8-9 pair is also incorrect. Thanks for all the lessons and logic. You have made this game a lot more fun for me :-)
The XY wing was a real time saver which I didn't spot. I solved the puzzle by eliminating the 1 from R1C6. It forces R5C6 to be 8, R5C5 to be 7 and R2C5 to be 8. Meanwhile the unique rectangle on (5,7) in (R2C4 to R3C8) makes R3C8 a 3, so R7C8 is 4, R7C9 is 2, R2C9 is 8, and R2C5 is 7. This is a contradiction, so R1C6 can't be 1. Writing software is good practice for solving sudokus. You frequently have to keep a dozen or more variables in your head at a time.
Plodding along got me a finish time of 16:40... now I'm watching to see how to cut this time down. Been doing Sudoku for a decade... on a plateau for years. I guess, if not faster, at least I'll have an appreciation for well-designed puzzles. And Simon's brilliance. 👏👏👏
At 13:12 you could have noticed that the 8 must be in the c4r7 position, and cannot be in c6r7, because otherwise the puzzle does not have a single solution: the 5s and 9s can then be interchanged in the same box.
Thanks, you've educated me on a new trick which is utilizing pivots. In time I will become more aware and recognize opportunities for these. Happy 2020 to all, happy solving! Lots of love from Las Vegas, Nevada.
As a point of interest, there is a uniqueness argument available at 13:45. Neither r7c4 nor r9c4 can be a 5, because this would create a closed arrangement of 5s and 9s in the lower-left portion of the grid that would have two solutions. Unfortunately this doesn't quite finish off the puzzle!
@@andjelacvetanovic2806 for me, I go ahead and include 3-in-a-row digits from the beginning. Otherwise, any possible triples are more difficult for me to see. But I find it really helps to restrict the pencil marking and then only add more markings as they become revealed... much less confusing. Of course, the key is deducing or intuiting the most effective moves as you get into the "conundrums". Hitting on the best order of solving makes a huge difference in time. Simon has a knack for spotting them.
Thank you for the video. I enjoyed solving the puzzle before I watched your approach. Just over nine minutes into the video, you realise that in column 8 both R5 and R9 must be either 8 or 9, then surely that means R4 in column 8 MUST be 2. Since C8R4 must be 2, then C8R5 must be 9 and therefore C7R4 must be 8! Where is the need for forming a 2-and-8 pair?
Classic "Pointing Pair". With R5C8 and R9C8, we have a pair that both can only be 8 or 9. Therefore all other boxes in Column 8 (R1,2,3,4,7) cannot have 8 or 9 in them. Importantly R4C8 cannot be 9. Also R4C7 cannot be 9, so that only leaves R5C8 for the 9.
Correction : In my reply above I said classic "Pointing Pair". This should be classic "Naked Pair". An explanation of these terms can be found at Andrew Stuart's www.sudokuwiki.org site.
@@brahmarathod That is libelously incorrect. If you bother to carefully watch and listen to what he says, he explains all of his logic. There is no cheating involved. At 9:05 he pointed out that r9c8 could only hold an 89 pair*, but didn't pencil it in because he was trying to stick studiously to Snyder notation in this video. He just made a mental note of it. Then at 9:21 he determined that box 6 needed 289, and that since the 2 was already fixed into r4c78, r5c8 was also an 89 pair. With 89 pairs locked into r5c8 and r9c8, he could eliminate the 9 in r4c8. That left R5c8 as the only cell left in the box that could contain a 9. * (Actually, the 9 had also already been eliminated because of the pair in c9r78, but he didn't catch that one.)
@@darrelleldridge4914 If I have to make more than one 50/50 guess that means I chose the wrong pair to start my guess on. To me, who does the daily sudoku in the newspaper, that means if I have to break out the pencil and eraser it is diabolical.
RBCharger Yes, you can study the distribution of the puzzle and make the first 50:50 guess to give you the most bang for the buck, but as you said, if you need to break out the pencil and eraser then it Definitely is diabolical, and I’ve had some that I’ve had to restart several times that I Definitely would consider diabolical!
"why can't 8 be in second column." Column 1 requires an 8. There is an 8 in the bottom 3x3, the 8 can't go in any of those cells. Row 6 contains 4. 8, then, is the only choice for that cell.
My usual method is to solve everything I can without writing and then to systematically go from 1 to 9 in each block writing down all the possibilities. As I do so I use the ghost number to eliminate options. Then I use strategies for eliminating numbers and finding where they go while constantly searching for anything that is obvious use to the elimination process. It won't win any tournaments, but it is systematic and good for a relaxing game.
He wrote 8 on A6 because you cant write any other number on A6 if you look it at that way. That row already has 1, 2, 3 & 4 and the column has 5, 6, 7 & 9 which forces A6 to be 8.
I used to do a lot of sudoku puzzles, went through all imaginable techniques, but there are some of them that are just impossible to calculate, you have to guess. I gave those to the other guys to try, they couldn't break 'em either. I hate those.
At 8:58 in r9c8, there must be an 8 because all we need is 5,8 and 9 in the row 9 and 5 can't be there as well as 9 because there are two small 9's in r4c8 and r5c8. And I don't get it that how can you write 9 in the r5c8. Can anyone explain me??
Once we find the 89 pair in r5c8 & r9c8, we know that one of these two squares MUST contain a 9 (and, of course the other will be an 8). Now, in the middle right 3x3 block, I've already pencil-marked 9s into either r4c8 or r5c8. If the 9 is in r4c8 then, because we know that there is exactly one 9 in r5c8 & r9c8, there would now be two 9s in col 8 - clearly impossible. In other words, there cannot be a 9 in r4c8 - therefore, as my pencil-marks tell me there is a 9 in either r4c8 or r5c8, the 9 must go in r5c8.Sorry if I didn't spend enough time explaining this clearly in the video!
@@CrackingTheCryptic Oh I see. That was my problem as well. I suppose it might be easier to just say that r9c8=8,9 and since a 9 is in either r4c8 or r5c8 this means that r9c8 is an 8. Then everything would naturally fall into place.
Cracking The Cryptic Sorry, but I still don't get it. What about r7c8? Could that not be a 9? How do you determine that r5c8 is a 9, when r5c8 and r9c8 are Not in fact a locked off pair? Okay, now I get it. In both those squares the only two options are an 8 or a 9; therefore they are a locked off pairing. Brilliant deduction.
Yes, I would like to know about that '9' in r5c8 also. It seemed to be a lucky guess to me. He seemed to completely miss the pair of pointing 9's eliminating the 9 in r9c8 as you correctly state. This puzzle would be rated as 'Gentle' in Andrew Stewarts SudoWiki.
I personally dont like the strategy of parking "pairs" right of the start. Usually diabolical sudokus would allow you to plug in about 4 different numbers, by simply doing horizontal and vertical checking. Then I try to lock 2 pairs only in 2 spots and circle them. Then I go to numbering all the empty squares.
This is not a diabolical puzzle. This is just an expert puzzle with difficulty of 5.4. XY-wing is not an advanced technique by any means. Diabolical puzzle is of a difficulty 7+, meaning you need at least something like a finned swordfish or a forcing chain.
Please to enjoy this video, you need to already have some Sudoku skills and try to solve it first alone. I did that so many times and with different way, I succeded to crack the puzzle.
If you take that cell and look at all the numbers that are already used horizontally, vertically and within that 3x3 block, the only unique number that's not been used yet is 7.
That 8 you placed at the 18 minute mark had me absolutely stuck! I am just starting at this and I print them out and use a pen, and the method you recommend of making pencil marks when a digit can only go in two cells in a 3 by 3 block. With this method, spotting that Y-wing was really hard for me. Is the term a Y-wing or a "bent triple" ?? I can see the logic behind it and I find it lovely, but hard to spot without also using pencil marks for cases when a given cell can only contain a contain a certain two digits (regardless if one of those two digits can go into many other cells in the 3x3 block).
I would suggest using two different kinds of pencil marks, like they do now on their Web app or android app. When a number can be restricted to two positions in a box, write it in the corners. But when you can find a square where only two digits can go, write it in the middle. Then you can easily keep track of both things without it being too confusing. But even with that, it is still very difficult to spot, I guess what you need then is experience, so keep practicing :)
I was able to solve this in a reasonable amount of time (less than an hour) by guessing two times, but the Y-wing is a lot faster and more elegant. I wouldn't have spotted it on my own.
I've tried pencil marks before but it always cluttered my mind In doing so, so I stopped doing it and I could see clearer on how to solve it if i just remembered.
The 9 in r2c7 forces there to be a 9 in either r4c8 or r5c8. (This is why there are pencil-marked 9s in the 3x3 block at this point of the solve). I then note in the commentary that r9c8 can only be an 8 or a 9. But this is exactly the same as r5c8 ie this square can also only be an 8 or a 9 (because the 2s in its 3x3 block are definitely in row 4). So as we now know the 9 in col 8 will either be in row 5 or row 9 it CANNOT be in r4c8 anymore.
Idont really want to spoil this for myself. can one do this puzzle using logically deductive processes or does it require a special rule like that wizards sudoku?
This is impossible to watch given the mouse is going all over the place. It's incredibly distracting when you are trying to listen and follow the board.
@@simonanthony8961 Unfortunately, that was a random game on my phone, I won't be able to find it again. But be sure I will send you the next one causing trouble!
Simon Anthony, I used to do sudoku at www.sudoku.org.uk/Daily.asp. The Friday and Sunday puzzles are listed as Diabolical. In my experience, those always came down to a guess, and solvers that I tried on them, with step by step solutions agreed. But that doesn't mean that human solvers in the forums at www.dailysudoku.com/sudoku/ don't have more exotic logical techniques beyond my comprehension.
Question: When you explained the y-wing, (which is a logical mechanism I hadn't organically uncovered on my own, thanks for the insight) you pointed out that if the 2/3 pair in r1c7 we're a 2, then r2c9 would be an 8. Half a moment later you concluded that r2c9 was indeed an 8. Is it then possible to logically infer that r1c7 is a 2 despite the other possible locations for 2 in that row? Such a resolution is part of the final solution, but I'm curious if that is simply a fluke, or if it is a pattern that would stand in other puzzles. Anyone have an insight on that?
In my experience sudoku that come down to an xy-wing (most common term I've seen) almost always lead immediately to an easy finish to the puzzle as it did in this case. I never paid attention to whether the pivot was the first cell to go. But I've seen puzzles that required two or three xy-wings, or presented several of them at the same time where only one of them was crucial. Check out www.dailysudoku.com/sudoku/ Their Very Hard puzzles are the ones I encountered these situations. They also have a discussion forum where members always publish solutions to the VH puzzles.
I don't think that 5 was forced. I get what he's doing, sharing the 5 between row 8 and column 7. But he hadnt yet ruled out the 5 in column 6 of that same row 8.
@@coachtim6188 It's interesting to see how many people are missing this one. I wonder what's making it so difficult. It's a simple naked single. Try all the numbers. You'll find that all of the other numbers are blocked. The way he found it, however, was by first figuring that the four empty cells in c7 needed 2358, then seeing that 238 already existed in r8.
If you look at row 4, we still need to place a 2 in the row. However at this point in the solve there are only three open spaces left in this row: we know the 2 cannot go in row 4 col 6 because of the 2 in the central 3x3, so it must go in the two squares r4c7 or r4c8.
"Why do that when a 2 also could possibly go in row 5 column 8." The 9 in the 3x3 above and the 7 in the 3x3 below determine that only a 7 or 9 can be placed in that cell.
It's because the 2 in r6c5 interacts with the centre-left block such that a 2 is forced into either r5c1, r5c2 or r5c3 - so I know the 2s in the centre-right block are forced into row 4.
@@CrackingTheCryptic OK, cool thanks. I see it now. I just learned the rules 5 days ago, can power my through easy, medium, and hard on sudoku.com but expert is still beyond me. Thanks for the tips!
"why can't there be a 2 in the middle square?" The 9 in the 3x3 above and the 7 in the 3x3 below determine that only a 7 or 9 can be placed in that cell.
First at 8:06 he put a 5 in R8C7, not C6, however, you can easily see why it must be a 5. If you look, row 8 has a 1, 2, 3, and 8 while column 7 has a 4, 6, 7, and 9 so the only number not utilized on that intersection is a 5.
Because the 9 in the 6th region is in R5, means the 9 in the 4th region has to be in R6 as R4 is already full, and hence the 9 in the 5th region has to be in R4C6
That was far from a diabolical puzzle, difficult at best, but for a newspaper puzzle it would be diabolical for many. And your Y-wing is properly called an XY-wing since it involves two possibilities. Your presentation would be a lot clearer if you weren't running your cursor so fast and over parts of the puzzle that aren't relevant.
Terrible sound and too fast for me. So what is the "trick" this isn't a tutorial video. Just an expert solving a puzzle at his usual speed. Interesting maybe for advanced Sudoku puzzlers but no good for us learners.
at 4:52/20:03 why can r6c1 =8 ?? column c1 has possible candidates marked : ₄ , ₁, ₁ which I would add ₈ to get new possible candidates ₄ ₈ , ₁ ₈, ₁ ₈ . SOMEBODY PLEASE answer!
Column 1 is missing the numbers {1, 2, 4, 8}. The cell at column 1 row 6, can see the numbers {1, 2, 4}. Since it can't be any of those numbers, and the 3 remaining cells in column 1 must then be a {1,2 or 4}, then R6 C1 must be an 8.
Are you just showing off how good you are, or trying to teach people how to solve difficult puzzles? Because you are penciling in so fast, I can't keep up at all, and will just have to look elsewhere. Us slowpokes need a bit more time, but then we can't all be champions, can we?
Indeed. I found this video useless probably partly because I skipped through in small increments for this exact reason and never heard the word y-wing. -1
I literally solved this one in my head. I didn't even need to write it down. It's too easy. But then again, I have been solving harder Sudokus for a while now. There's this magazine called "Sudoku Grandmasters". That's the one that I practice with.
@@cbrudder84 Well, I don't like to brag but since you started it: I have one of the highest recorded IQs in Germany. According to my psychologist only around 40 people have achieved test scores this high in all German-speaking countries (this includes Germany, Austria, and Switzerland). Proof: facebook.com/1717043838583030/posts/1814725545481525/ My brain was also studied by researchers because of my unusually high memory retention. I can accurately recall about 80% of all the visual and auditive stimuli that I'm exposed to. I have been on RUclips for a long time and if I got a penny for every time that someone wrote a comment that referred to r/iamverysmart I'd be a millionaire by now. Actually smart people don't use Reddit (I don't, and neither do any of my friends who also happen to have 140+ IQs). Reddit is plagued by its tribalist herd mentality. The only things that get upvoted on that platform are popular opinions. It is therefore not a platform that's very conducive to inquiry-based learning. I will sequester myself for now.
@@AntonioKowatsch You state: "Reddit is plagued by its tribalist herd mentality." Only a redditor would know this. You may have contradicted yourself, which is something unbecoming of someone with 140+ IQ.
@@Roanish lets be straight. that guy is a complete twat but i think its entirely okay to use something like reddit enough before realizing it isnt for you. the fact that you know enough about something to not use is entirely fine in my eyes
The 3 in row 6 column 9 rules out a 3 in row 6. The 3 in row 2 column 6 rules out a 3 in column 6. The 3 pair in row 5 columns 1 and 2 rule out any other 3 in row 5. That leaves a 3 as the only possibility in row 4 column 4.
![Megan Thee Stallion - Neva Play (feat. RM) [Official Video]](http://i.ytimg.com/vi/TpYTyAaTRts/mqdefault.jpg)
You made 11000 people watch you solve a sudoku... You sir.. have a gift.
No. 90000.
99,000
100,000. Make that 100,001, and I almost never watch a RUclips video in its entirety. 😁
Niki C
Wow your patience is short
144K at the time I'm watching :p
I always enjoy watching you solve these puzzles Simon. Great job!
About R9C8 at that point in the puzzle. The 9th row needed 2, 5 & 9. However the R9C8 cell is forced to have written 8 because of the 5 in the little box along with the 9 pencil marks.
Thanks Mark. I slogged my way thru to the Y-wing point at 13:45 of the video and then got very stuck. Once the Y-Wing was used to eliminate the 8 at R1 C9, then the puzzle just unravelled quickly. Your video has made it much easier for me to learn how to spot and use Y-wings. Cheers
Yes, it's a new technique for me. I am going to look for it in some of the ones that have stumped me.
I have never tried Sudoku, but I understand your videos, and you are amazing at solving these.
At 9.07, there can only be an 8 whereas you say it must be an 8-9 pair. A 9 cannot go there. After that I believe your analysis of the next 8-9 pair is also incorrect. Thanks for all the lessons and logic. You have made this game a lot more fun for me :-)
Exactly! tried to understand it but finally got that it was an error.
That was really helpful thank you. I was having real trouble with my first expert puzzle until now.
The XY wing was a real time saver which I didn't spot. I solved the puzzle by eliminating the 1 from R1C6. It forces R5C6 to be 8, R5C5 to be 7 and R2C5 to be 8. Meanwhile the unique rectangle on (5,7) in (R2C4 to R3C8) makes R3C8 a 3, so R7C8 is 4, R7C9 is 2, R2C9 is 8, and R2C5 is 7. This is a contradiction, so R1C6 can't be 1.
Writing software is good practice for solving sudokus. You frequently have to keep a dozen or more variables in your head at a time.
Plodding along got me a finish time of 16:40... now I'm watching to see how to cut this time down. Been doing Sudoku for a decade... on a plateau for years.
I guess, if not faster, at least I'll have an appreciation for well-designed puzzles. And Simon's brilliance. 👏👏👏
what application are you using?
in case you never found an answer, duncan's sudoku solver
I like Excel better because you can copy the entire puzzle if you if you want to go down a path
For the first time, I finally see that Snyder notation simplifies identification of Y-Wings. Better late than never, eh? Thanks!
At 13:12 you could have noticed that the 8 must be in the c4r7 position, and cannot be in c6r7, because otherwise the puzzle does not have a single solution: the 5s and 9s can then be interchanged in the same box.
Thanks for pointing that out, I too missed it while solving the puzzle. I guess my sudoku skills are a bit rusty.
Good trick at 17:30, it's the puzzle solver; sometimes you need to use it more than once.
Great video - please increase the sound difficult to hear. Thank you.
Thanks, you've educated me on a new trick which is utilizing pivots. In time I will become more aware and recognize opportunities for these. Happy 2020 to all, happy solving! Lots of love from Las Vegas, Nevada.
Brilliant!!
Its you!
As a point of interest, there is a uniqueness argument available at 13:45. Neither r7c4 nor r9c4 can be a 5, because this would create a closed arrangement of 5s and 9s in the lower-left portion of the grid that would have two solutions.
Unfortunately this doesn't quite finish off the puzzle!
That's an excellent point Sam... I may do (another!) follow up video just on that point :).
That "Y" wing did the trick for me. Need to recognize this and the pivot cell! *thank you*
Helpful???? Bleeding Eureka that “Y-wing” - loved it - you can watch all the sparring but the knockout comes 17:00 - 17:40 - ....... next please. 👍
thx, helped a lot ! i made way to many pencil marks at the beginning.
musikk83 why is it bad to use too many pencil marks? I can’t solve it if I dont use all of them 😅
@@andjelacvetanovic2806 its easier find the pairs, triples, etc
@@andjelacvetanovic2806 for me, I go ahead and include 3-in-a-row digits from the beginning. Otherwise, any possible triples are more difficult for me to see. But I find it really helps to restrict the pencil marking and then only add more markings as they become revealed... much less confusing.
Of course, the key is deducing or intuiting the most effective moves as you get into the "conundrums". Hitting on the best order of solving makes a huge difference in time. Simon has a knack for spotting them.
Thank you for the video. I enjoyed solving the puzzle before I watched your approach.
Just over nine minutes into the video, you realise that in column 8 both R5 and R9 must be either 8 or 9, then surely that means R4 in column 8 MUST be 2. Since C8R4 must be 2, then C8R5 must be 9 and therefore C7R4 must be 8! Where is the need for forming a 2-and-8 pair?
He said "Pencil mark" 32 times. 21 in the first 5 mins xD
Classic "Pointing Pair". With R5C8 and R9C8, we have a pair that both can only be 8 or 9. Therefore all other boxes in Column 8 (R1,2,3,4,7) cannot have 8 or 9 in them. Importantly R4C8 cannot be 9. Also R4C7 cannot be 9, so that only leaves R5C8 for the 9.
Correction : In my reply above I said classic "Pointing Pair". This should be classic "Naked Pair". An explanation of these terms can be found at Andrew Stuart's www.sudokuwiki.org site.
5:30 : you already know where to place the 1 and 2 in the first column
9:34 he writes 9 in that box so confidently whereas 8 was also the option he has solution to this he's just good actor guys
@@brahmarathod That is libelously incorrect. If you bother to carefully watch and listen to what he says, he explains all of his logic. There is no cheating involved.
At 9:05 he pointed out that r9c8 could only hold an 89 pair*, but didn't pencil it in because he was trying to stick studiously to Snyder notation in this video. He just made a mental note of it.
Then at 9:21 he determined that box 6 needed 289, and that since the 2 was already fixed into r4c78, r5c8 was also an 89 pair.
With 89 pairs locked into r5c8 and r9c8, he could eliminate the 9 in r4c8. That left R5c8 as the only cell left in the box that could contain a 9.
* (Actually, the 9 had also already been eliminated because of the pair in c9r78, but he didn't catch that one.)
i feel like a cat trying to catch the cursor.
This is not a diabolical puzzle.
Then what is it Kevin?
Sylvia Carlson if you have to make 1 50:50 guess then it’s hard, if you have to make multiple 50:50 guesses then it’s diabolical!
@@darrelleldridge4914 If I have to make more than one 50/50 guess that means I chose the wrong pair to start my guess on. To me, who does the daily sudoku in the newspaper, that means if I have to break out the pencil and eraser it is diabolical.
RBCharger
Yes, you can study the distribution of the puzzle and make the first 50:50 guess to give you the most bang for the buck, but as you said, if you need to break out the pencil and eraser then it Definitely is diabolical, and I’ve had some that I’ve had to restart several times that I Definitely would consider diabolical!
The only acceptable clickbait video
Or. I found another way by skyscraper (L1C2-L3C2) (L1C9-L2C9)... =8 in L1C6... ... etc.
SIR SIMON tell me if you are correct!
Please.
this one had few of x wings too, not so high level of diabolical puzzle when you can solve it with x wing without even using that xy wing
4:48 why can't 8 be in second column..
"why can't 8 be in second column."
Column 1 requires an 8. There is an 8 in the bottom 3x3, the 8 can't go in any of those cells. Row 6 contains 4. 8, then, is the only choice for that cell.
Thank you
My problem with Sudoku's is that in the time it takes to solve this puzzle I could have coded my own Sudoku solver.
Doesn’t really seem diabolical difficulty.
My usual method is to solve everything I can without writing and then to systematically go from 1 to 9 in each block writing down all the possibilities. As I do so I use the ghost number to eliminate options. Then I use strategies for eliminating numbers and finding where they go while constantly searching for anything that is obvious use to the elimination process. It won't win any tournaments, but it is systematic and good for a relaxing game.
I think ive been missing y wings
Hi! At min: 4:49 you put an 8 in A6... I really don't get it (A2 could be an 8 as well).
He wrote 8 on A6 because you cant write any other number on A6 if you look it at that way. That row already has 1, 2, 3 & 4 and the column has 5, 6, 7 & 9 which forces A6 to be 8.
Thank you,@@FazalFariz !! i'm blind... it was so obvious. Cheers!
@@republicofthegrave Haha. That's the whole point of the game. To miss the obvious. Cheers!
I used to do a lot of sudoku puzzles, went through all imaginable techniques, but there are some of them that are just impossible to calculate, you have to guess. I gave those to the other guys to try, they couldn't break 'em either. I hate those.
What's that software you're using in the video, please?
I would love to know also. Thanks.
Me three. Anyone???
It seems it is Duncan's SuDoku Solver
@@xenmax Yes It is.. Thanks
At 8:58 in r9c8, there must be an 8 because all we need is 5,8 and 9 in the row 9 and 5 can't be there as well as 9 because there are two small 9's in r4c8 and r5c8.
And I don't get it that how can you write 9 in the r5c8. Can anyone explain me??
Once R9C8 becomes an 8 that forces the 8 into R4C7. R5C8 cannot be a 2 forcing the 9 there. That's at least how I read it.
Once we find the 89 pair in r5c8 & r9c8, we know that one of these two squares MUST contain a 9 (and, of course the other will be an 8). Now, in the middle right 3x3 block, I've already pencil-marked 9s into either r4c8 or r5c8. If the 9 is in r4c8 then, because we know that there is exactly one 9 in r5c8 & r9c8, there would now be two 9s in col 8 - clearly impossible. In other words, there cannot be a 9 in r4c8 - therefore, as my pencil-marks tell me there is a 9 in either r4c8 or r5c8, the 9 must go in r5c8.Sorry if I didn't spend enough time explaining this clearly in the video!
@@CrackingTheCryptic Oh I see. That was my problem as well. I suppose it might be easier to just say that r9c8=8,9 and since a 9 is in either r4c8 or r5c8 this means that r9c8 is an 8. Then everything would naturally fall into place.
Cracking The Cryptic Sorry, but I still don't get it. What about r7c8? Could that not be a 9? How do you determine that r5c8 is a 9, when r5c8 and r9c8 are Not in fact a locked off pair? Okay, now I get it. In both those squares the only two options are an 8 or a 9; therefore they are a locked off pairing. Brilliant deduction.
Yes, I would like to know about that '9' in r5c8 also. It seemed to be a lucky guess to me. He seemed to completely miss the pair of pointing 9's eliminating the 9 in r9c8 as you correctly state. This puzzle would be rated as 'Gentle' in Andrew Stewarts SudoWiki.
you’re too good for me m8
I personally dont like the strategy of parking "pairs" right of the start. Usually diabolical sudokus would allow you to plug in about 4 different numbers, by simply doing horizontal and vertical checking. Then I try to lock 2 pairs only in 2 spots and circle them. Then I go to numbering all the empty squares.
I can't keep up. I need to go a lot slower. 😩 Wish I had your brains. Maybe I have other talents though. 🤔
This is not a diabolical puzzle. This is just an expert puzzle with difficulty of 5.4. XY-wing is not an advanced technique by any means. Diabolical puzzle is of a difficulty 7+, meaning you need at least something like a finned swordfish or a forcing chain.
Please to enjoy this video, you need to already have some Sudoku skills and try to solve it first alone. I did that so many times and with different way, I succeded to crack the puzzle.
Dont understand the 5 at 8.20
7:37 how you sure in row 6, column 7, is 7?
If you take that cell and look at all the numbers that are already used horizontally, vertically and within that 3x3 block, the only unique number that's not been used yet is 7.
That 8 you placed at the 18 minute mark had me absolutely stuck! I am just starting at this and I print them out and use a pen, and the method you recommend of making pencil marks when a digit can only go in two cells in a 3 by 3 block. With this method, spotting that Y-wing was really hard for me. Is the term a Y-wing or a "bent triple" ?? I can see the logic behind it and I find it lovely, but hard to spot without also using pencil marks for cases when a given cell can only contain a contain a certain two digits (regardless if one of those two digits can go into many other cells in the 3x3 block).
I would suggest using two different kinds of pencil marks, like they do now on their Web app or android app. When a number can be restricted to two positions in a box, write it in the corners. But when you can find a square where only two digits can go, write it in the middle. Then you can easily keep track of both things without it being too confusing.
But even with that, it is still very difficult to spot, I guess what you need then is experience, so keep practicing :)
I was able to solve this in a reasonable amount of time (less than an hour) by guessing two times, but the Y-wing is a lot faster and more elegant. I wouldn't have spotted it on my own.
I've tried pencil marks before but it always cluttered my mind In doing so, so I stopped doing it and I could see clearer on how to solve it if i just remembered.
Train your memory by solving the entire Sudoku without writing anything down.
At 9:30 , why does R5C8 have to be a 9?
The 9 in r2c7 forces there to be a 9 in either r4c8 or r5c8. (This is why there are pencil-marked 9s in the 3x3 block at this point of the solve). I then note in the commentary that r9c8 can only be an 8 or a 9. But this is exactly the same as r5c8 ie this square can also only be an 8 or a 9 (because the 2s in its 3x3 block are definitely in row 4). So as we now know the 9 in col 8 will either be in row 5 or row 9 it CANNOT be in r4c8 anymore.
Idont really want to spoil this for myself. can one do this puzzle using logically deductive processes or does it require a special rule like that wizards sudoku?
No special esoteric rules! Good luck ;)
HELLO
I have a sudoku
Unable to solve
Sneaky cuts 13:50
16:30 is what you were looking for😉
What app are you using sir?
The app used in this video is Duncan's SuDoku Solver
This is impossible to watch given the mouse is going all over the place. It's incredibly distracting when you are trying to listen and follow the board.
Honestly, that puzzle wasn't that hard, I already got stuck on a single grid for hours not being able to solve it without guessing and backtracking...
Maxence1402a Send it over to us at @crypticcracking we love trying to figure out extreme sudoku!
@@simonanthony8961 Unfortunately, that was a random game on my phone, I won't be able to find it again. But be sure I will send you the next one causing trouble!
Simon Anthony,
I used to do sudoku at www.sudoku.org.uk/Daily.asp. The Friday and Sunday puzzles are listed as Diabolical. In my experience, those always came down to a guess, and solvers that I tried on them, with step by step solutions agreed. But that doesn't mean that human solvers in the forums at www.dailysudoku.com/sudoku/ don't have more exotic logical techniques beyond my comprehension.
Not so diabolical. I didn't need to find tthe Y wing, I don't know why.
That's my trick too! I came up with it by myself:)
At 8:20 how does he know that the 5 is a hidden single?
In column 7 you can only have {2, 3, 5, 8}; in row 8 there is already {2, 3, 8} so that only leaves a 5 for the intersecting cell :)
Question: When you explained the y-wing, (which is a logical mechanism I hadn't organically uncovered on my own, thanks for the insight) you pointed out that if the 2/3 pair in r1c7 we're a 2, then r2c9 would be an 8. Half a moment later you concluded that r2c9 was indeed an 8. Is it then possible to logically infer that r1c7 is a 2 despite the other possible locations for 2 in that row? Such a resolution is part of the final solution, but I'm curious if that is simply a fluke, or if it is a pattern that would stand in other puzzles. Anyone have an insight on that?
In my experience sudoku that come down to an xy-wing (most common term I've seen) almost always lead immediately to an easy finish to the puzzle as it did in this case. I never paid attention to whether the pivot was the first cell to go. But I've seen puzzles that required two or three xy-wings, or presented several of them at the same time where only one of them was crucial. Check out www.dailysudoku.com/sudoku/ Their Very Hard puzzles are the ones I encountered these situations. They also have a discussion forum where members always publish solutions to the VH puzzles.
At 8:10, he says 238 in row 8, therefore this has to be a 5, r8c7. Why?
I don't think that 5 was forced. I get what he's doing, sharing the 5 between row 8 and column 7. But he hadnt yet ruled out the 5 in column 6 of that same row 8.
@@coachtim6188 It's interesting to see how many people are missing this one. I wonder what's making it so difficult.
It's a simple naked single. Try all the numbers. You'll find that all of the other numbers are blocked.
The way he found it, however, was by first figuring that the four empty cells in c7 needed 2358, then seeing that 238 already existed in r8.
It took him so long to find c7r9 is an 8.............
At minute 3:50, you placed two 2s in row 4 columns 78. Why do that when a 2 also could possibly go in row 5 column 8.
If you look at row 4, we still need to place a 2 in the row. However at this point in the solve there are only three open spaces left in this row: we know the 2 cannot go in row 4 col 6 because of the 2 in the central 3x3, so it must go in the two squares r4c7 or r4c8.
@@CrackingTheCryptic or alternatively, twos are locked to r5c123, which eliminates a two in r5c8
"Why do that when a 2 also could possibly go in row 5 column 8."
The 9 in the 3x3 above and the 7 in the 3x3 below determine that only a 7 or 9 can be placed in that cell.
At 3:46 you place 2s in the center-right block, why can't there be a 2 in the middle square?
Because row 4 columns 1-3 can't contain a 2
It's because the 2 in r6c5 interacts with the centre-left block such that a 2 is forced into either r5c1, r5c2 or r5c3 - so I know the 2s in the centre-right block are forced into row 4.
@@CrackingTheCryptic OK, cool thanks. I see it now. I just learned the rules 5 days ago, can power my through easy, medium, and hard on sudoku.com but expert is still beyond me. Thanks for the tips!
"why can't there be a 2 in the middle square?"
The 9 in the 3x3 above and the 7 in the 3x3 below determine that only a 7 or 9 can be placed in that cell.
What made you put a 5 in R8C6 at 8:06?
First at 8:06 he put a 5 in R8C7, not C6, however, you can easily see why it must be a 5. If you look, row 8 has a 1, 2, 3, and 8 while column 7 has a 4, 6, 7, and 9 so the only number not utilized on that intersection is a 5.
Which program do you use?
The app used in this video is Duncan's SuDoku Solver
At 9:55 how do you know R6C6 isn’t a 9?
Because the 9 in the 6th region is in R5, means the 9 in the 4th region has to be in R6 as R4 is already full, and hence the 9 in the 5th region has to be in R4C6
handofthesly yes, I see! Thanks
What is the trick? I have only 5 Minutes for it.
In 5 minutes you will not solve a Sudoku. It takes at least 10 - 15 minutes.
When the Sudoku is very hard i sometimes need 40 minutes
That was far from a diabolical puzzle, difficult at best, but for a newspaper puzzle it would be diabolical for many.
And your Y-wing is properly called an XY-wing since it involves two possibilities. Your presentation would be a lot clearer if you weren't running your cursor so fast and over parts of the puzzle that aren't relevant.
Terrible sound and too fast for me. So what is the "trick" this isn't a tutorial video. Just an expert solving a puzzle at his usual speed. Interesting maybe for advanced Sudoku puzzlers but no good for us learners.
16:30
You’re getting it done, you’re not doing it. It’s like homework. Doing the homework requires a lot more thought than just getting it done.
This is not Diabolical level. Way too easy!
I hate this sound quality SOOO much
at 4:52/20:03 why can r6c1 =8 ?? column c1 has possible candidates marked : ₄ , ₁, ₁
which I would add ₈ to get new possible candidates ₄ ₈ , ₁ ₈, ₁ ₈ . SOMEBODY PLEASE answer!
Column 1 is missing the numbers {1, 2, 4, 8}. The cell at column 1 row 6, can see the numbers {1, 2, 4}. Since it can't be any of those numbers, and the 3 remaining cells in column 1 must then be a {1,2 or 4}, then R6 C1 must be an 8.
Are you just showing off how good you are, or trying to teach people how to solve difficult puzzles? Because you are penciling in so fast, I can't keep up at all, and will just have to look elsewhere. Us slowpokes need a bit more time, but then we can't all be champions, can we?
Yeah, I guess not
If you look carefully at the screen you'll see there is a pause button. FYI you can also rewind.
The penciling should be easy thing. I dont actually bother to keep up. Just focus on the difficult part.
Indeed. I found this video useless probably partly because I skipped through in small increments for this exact reason and never heard the word y-wing. -1
not really that hard to solve.
B bb
isn't 17 the lowest number of "numbers" a Sudoku must have to be unique solveable? So this is far from diabolical...
Difficult to follow, you are too fast at the beginning then suddenly you are stuck. A good teacher should prepare in advance
I hate the way he solves these puzzles, the lack of a logical approach drives me crazy.
I literally solved this one in my head. I didn't even need to write it down. It's too easy.
But then again, I have been solving harder Sudokus for a while now. There's this magazine called "Sudoku Grandmasters". That's the one that I practice with.
lolol r/iamverysmart gold material right here.
@@cbrudder84 Well, I don't like to brag but since you started it:
I have one of the highest recorded IQs in Germany. According to my psychologist only around 40 people have achieved test scores this high in all German-speaking countries (this includes Germany, Austria, and Switzerland). Proof: facebook.com/1717043838583030/posts/1814725545481525/
My brain was also studied by researchers because of my unusually high memory retention. I can accurately recall about 80% of all the visual and auditive stimuli that I'm exposed to.
I have been on RUclips for a long time and if I got a penny for every time that someone wrote a comment that referred to r/iamverysmart I'd be a millionaire by now.
Actually smart people don't use Reddit (I don't, and neither do any of my friends who also happen to have 140+ IQs). Reddit is plagued by its tribalist herd mentality. The only things that get upvoted on that platform are popular opinions. It is therefore not a platform that's very conducive to inquiry-based learning.
I will sequester myself for now.
@@AntonioKowatsch oh my god, this is amazing! Hahaha what a dumbass!
@@AntonioKowatsch You state: "Reddit is plagued by its tribalist herd mentality." Only a redditor would know this. You may have contradicted yourself, which is something unbecoming of someone with 140+ IQ.
@@Roanish lets be straight. that guy is a complete twat but i think its entirely okay to use something like reddit enough before realizing it isnt for you. the fact that you know enough about something to not use is entirely fine in my eyes
What a dreadful tutorial!You can't hear him or make out what he's doing!Check out the American dude, he's far superior!(my lame animations)
2:39 how you sure in row 4, column 4, is 3?
The 3 in row 6 column 9 rules out a 3 in row 6. The 3 in row 2 column 6 rules out a 3 in column 6. The 3 pair in row 5 columns 1 and 2 rule out any other 3 in row 5. That leaves a 3 as the only possibility in row 4 column 4.
oh i see thx.. you right...