The Sudoku You Should Not Enjoy Solving

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Today's puzzle was published 23 hours ago! So this is a sort of bonus, exploring some of the channel's background, and trying to explain why we prefer handmade puzzles to computer-generated sudoku. The puzzle Mark tries is available at app.crackingthecryptic.com/su...
Normal sudoku rules apply.
The version of the puzzle that Mark solves is missing two given 4s that appear in the correct version above, and therefore the version he is attempting actually DOES have two solutions! However, the ‘solve path’ is basically exactly the same!
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Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the twelve-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.
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▶ Contents ◀
0:00 Theme Music & a chat about what the channel and this video are all about
7:50 Start Of Solve - Let's Get Cracking!

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5 авг 2024

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Комментарии : 154

@flobiish 11 месяцев назад

LOL @3:04 "There is never an alternate solution to one of our puzzles. We only publish puzzles which have only one solution." @3:10 with a big magenta background, "Except this one." I had to take a break to stop laughing.

@spelldaddy5386 11 месяцев назад

Fun fact: any 9x9 classic sudoku needs to have at least eight unique given digits. We could have looked at Mark's original grid, seen that there were no 4s or 8s, and immediately known that it was not unique

@SmartHobbies 11 месяцев назад

I did not know that. Is there a source document or link showing how this was figured out?

@spelldaddy5386 11 месяцев назад

@@SmartHobbies I don't know of any published works explaining this, but it is relatively simple to understand once you consider the framework of solving sudoku. Think about the two ways you can place digits in a classic sudoku. You either have a hidden single, where the presence of other digits x only allow x to go in one cell in a house (row/column/box), or you have a naked single, where every digit except x is pointing at a cell, forcing that cell to be x. If you think about it, any other logical step you might take, like wings, pairs, triples, etc. is just a more complex form of one of these two categories. Some variant rule sets have other ways to place digits, such as mathematical requirements, so this rule is only absolute for classics. Given these two categories, imagine a sudoku grid that has all the 1s, 2s, 3s, 4s, 5s, 6s, and 7s filled in, but there are no 8s or 9s. You cannot place a digit with a hidden single, because you need other identical digits to narrow down the possibilities. You cannot place a digit with a naked single, because every blank cell still has two possibilities. The puzzle is not unique, because if you arbitrarily choose one configuration for the 8s and the other for the 9s, you can just as easily switch the positions and have an equally valid solution. If, however, you had a given 8 somewhere, then that may be enough to disambiguate the 8s and 9s. Depending on the configuration of the grid and the remaining blank cells, it could require more than one given, which is why I say "may". Now, you don't need to have any given 9s in this scenario, because once you have enough given 8s to place the rest with hidden singles, you can also place the 9s with naked singles. And if you were curious, this same logic applies to any regular sudoku with size n, where you need at least n-1 unique given digits. You may find it interesting to play around with 4x4 grids, which don't take long to solve, but are big enough to illustrate this phenomenon. Just start plotting random given digits, try to solve the puzzle, then delete it all and repeat.

@ianhill5373 11 месяцев назад

@SmartHobbies if there are two digits that are completely missing from the grid (say x and y), then any valid solution would have a twin solution with x's and y's swapped round. After all there is no arithmetic meaning to the numbers in a classic sudoku, they are just 9 different symbols that you could swap for letters or colours or emojis or whatever you want.

@SmartHobbies 11 месяцев назад

@@ianhill5373 Thank you. I never thought about that until I saw that comment. Do you create Sudoku puzzles?

@inespm1 11 месяцев назад

Great bonus video! Not only it was a comprehensive introduction for newer viewers on solving stratagies, jargon and scanning, it was very amusing to watch as a long time subscriber because of the irony of fate 😂

@leickrobinson5186 11 месяцев назад

For whatever reason, I found this one to be much more fun than typical computer-generated puzzles. 🤔

@liamcallaghan95 11 месяцев назад

Brilliant video, Mark. As much as the 2x solutions wasn’t an ideal ending, the explanation as to the differences between computer-generated vs ‘handmade’ puzzles, plus the guidance re x-wings, y-wings and the different methods of marking, was incredibly insightful. Perhaps slightly basic to the seasoned sudoku veterans, but a real gem for any newbies to the channel (like me)! Thanks again, and a great watch as always.

@veggiet2009 11 месяцев назад

Mark: your shouldn't enjoy this Also Mark: wait, that's kinda clever

@legitimatebusinessman5537 11 месяцев назад

I don’t mind doing computer-generated classic sudokus (I solve the NYT sudokus most days). But my biggest problem with most of them is that the software doesn’t give you the notation flexibility that the CTC software does. So I have to choose between pencil marks being digits in a box vs. cell candidates, and can’t really distinguish between them. That slows down my solve quite a bit.

@GrantMcLean 11 месяцев назад

If you google for "Sudoku Exchange bookmarklets" you'll find a tool that allows you to open the NYC puzzle on an alternate site that does allow dual notation.

@heatherfyffe3618 11 месяцев назад

About 15 minutes for me and there was nothing fancier than xy pairs and triples. Really quite straightforward.

@warren_r 11 месяцев назад

This is great. A classic Sudoku. I always love it when Mark comes back to the basics.

@kevinerose 11 месяцев назад

Great explanations. I think it was the Y-wing which was the difficulty for this one. Glad you went over the y-wing too as it makes more sense to me now.

@stevieinselby 11 месяцев назад

I fully understand y-wings, and have done for a year or two following a couple of good videos on this channel a while back that explained them. Still doesn't mean that I can ever spot them in the wild though 😢

@Alex_Meadows 11 месяцев назад

@@stevieinselby Likewise! They make perfect sense to me, but I think I'm correct in saying that I've never noticed one myself.

@kevinerose 11 месяцев назад

@@stevieinselby I think it goes back to the "guessing" routine. The y-wing would be a "simple" guess of only 2-3 moves. Where the 2 numbered cell (let's call it the Pivot cell) forces a block of a different number in another cell. This is created by 2 "blocker" cells. The 2 blocker cells must be within the same Block, Row, or Column as the Pivot cell. The 2 blocker cells would contain the number in the "target" cell that would be blocked. So there are a total of 4 cells affected. 1 pivot cell, 2 blocker cells, and 1 target cell. They do look like they are tough to find and you would only find it while in "guessing mode". I imagine, while guessing, to review all cells with 2 digits. Then see if there are other 2 digits cells within the Block, Row, or Column with similar digits. Then look if there is a target cell.

@emilywilliams3237 11 месяцев назад

I never tire of hearing you or Simon tell about the origins of this channel, or talk about each other's solving techniques or location ("Mrs. Rochester" made me laugh). And you took the time to demonstrate and explain Snyder notation, which was a huge eye-opener to me when I first started watching the channel. The fact that you also were able to show an x-wing and a y-wing (and that you explained each so well) was a huge bonus. And of course there was the humor of the puzzle actually not having a unique solution as you were working on it! I loved this video - thanks for this "bonus," Mark.

@in_the_woods 11 месяцев назад

I enjoyed this... delightful to find Mark explaining his way out at the end.

@andyparkerson 11 месяцев назад

If the point was to show a sudoku that wasn't fun to solve, you made the point. I much prefer hand-generated sudokus with interesting solve paths.

@NetoSutam 11 месяцев назад

loved how you explained the different techniques throughout the solve! thanks for teaching!

@Kelters 11 месяцев назад

Straight forward puzzle. -- But then I had the advantage of the 4's! I also have the advantage of a few years of CtC training !! 😀

@zachb_20 11 месяцев назад

Straight forward to me because when I got stuck at the end I bifurcated and guessed correctly on the first try 😆

@jestfullgremblim8002 11 месяцев назад

I read CtC as "CQC" and though of Metal Gear😢

@istvanmagi473 11 месяцев назад

Even with the 4s on, it absolutely isn't straightforward. The end requires either bifurcation or some bizarre advanced techinque that I'm not aware of even after watching CtC for 3 years.

@Kelters 11 месяцев назад

@@istvanmagi473 Sorry to hear that. I used simple basic techniques such as pointing pairs found using Snyder notation. Never had to guess anything. I'm no genius, and many's the time I've had to watch a video of the solve of a puzzle only to find I missed something really simply like a hidden triple staring me in the face!

@longwaytotipperary 11 месяцев назад

Thank you so much for the bonus puzzle!! Hope you’re having a great holiday! Also enjoyed watching the opening explanations! ❤❤

@KestrelQ 11 месяцев назад

That was a really nice explanation of Y-Wings! As a huge novice, thank you for showing me :)

@eatdirtmofo 11 месяцев назад

Well, I found that pretty straight forward, now to watch Mark's solve. Ps, my favourite setter is Clover. I love how her puzzles unfold, like a carefully wrapped present.

@agargamer6759 11 месяцев назад

Oh the irony! Thanks for the entertaining bonus video Mark!

@guyb7005 11 месяцев назад

ahhhh - as a new viewer, I very much appreciate the introduction and explanation -- many thanks

@chocolateboy300 3 месяца назад

I finished in 14:28 minutes. This is why I don't usually do regular Sudokus anymore. I usually end up having to bifurcate the end and that makes the ending unsatisfying and frustrating. The thing I really like about variant Sudokus are the unique logic and many ways to get to that logic, by either using the internal logic of the puzzle (German Whispers never have 5s, Black Kropki dots can never have 5, 7, or 9, etc.), the external logic of the puzzle (Math, The Secret, Phistomefel's Ring, etc.), and Setter's Logic (SET Theory, Why would certain clues be placed, Previous Puzzles with similar logic, etc.). This gives a lowly skilled solver like me the opportunity to try a different method if I get stuck on some parts.

@d4r4butler74 11 месяцев назад

You are wonderful Mark.

@memyself8340 11 месяцев назад

Absolutely loved the history lesson sbout your channel. I've been watching for years and learned something new.

@stuartharris2165 11 месяцев назад

I think that computer generated sudoku do have a role when you first start solving sudoku, but when you get into it, you quickly notice that the logic used on these computer ones never really varies. However I loved todays puzzle taking us back to basics!!

@JorgePacker 11 месяцев назад

Thanks for doing this one Mark! Every now and then I get stuck on a computer generated sudoku and I'm always wondering how you would solve it (but I have never sent an email asking 😅). This was actually fun, and I'd suggest you add one of these examples once in a while... Cheers

@neil2796 11 месяцев назад

I'm definitely guilty of over pencil marking. I'm slowly getting the hang of Snyder notation.

@BozoTheBear 11 месяцев назад

God you're a BEAST, Mark!! I love watching Simon waltz through puzzles with elegant logic, but I also love watching Simon bulldoze like a boss!!

@MrMarcLaflamme 11 месяцев назад

I had no idea there was a world sudoku championship, let alone being hosted in Canada (and I checked out where and it's only about 6 hrs away!) Very cool! I wonder if you can spectate?

@ExodaCrown 11 месяцев назад

Yeah I have to agree about hard puzzles when made by a computer, you get to the end where you have to do insane logic like xyz wings which feels like guessing or something like BUG+1. The beginning you can solve most of it by asking where does the x goes then go through the numbers a few times before you need any harder logic. For this on when I got stuck at the end and not completely pencil marking I looked at r5c9 and used BUG and the puzzle fell apart. It probably the wrong situation to used BUG, but plugging in one of the digits that it was limited to two choices then following that logic can suck.

@leeprice133 2 месяца назад

Honestly I wouldn't regard XYZ-wings as particularly insane logic. It's more the long X/XY-chains that I think are people deceiving themselves into believing they are doing something other than bifurcation.

@sdsign4229 11 месяцев назад

This was a hilarious disaster of a video, and my first Mark video! Great work!

@user-km8xu9gc3y 11 месяцев назад

Thankss for the solve. It is not often that you see colouring and it is technique I use frequently I must admit I do like your method of colouring - I learnt something . For me the solution fell out with conflicting 6's in R2,C3 which then ended up dropping out a 48 pair in R2, leading to a 35,36,35 groupng in R2 - giving the 6 in R2C6.

@piarittersporn 11 месяцев назад

Beautiful puzzle.

@mastermicah9807 11 месяцев назад

Great video once again!

@guyb7005 11 месяцев назад

colour strategy is absurdly brilliant!

@nex 11 месяцев назад

I actually had some fun logic-ing this one out. Took me a long time because I'm inexperienced with such sudoku, but I've seen enough CTC to have a clue what to do. So, I'm kinda pleased I could solve it on my own - however, I absolutely *needed* the colouring tool. Getting this in an app without the colouring feature would have been pure frustration.

@michaelhoffman2011 11 месяцев назад

Really fun puzzle to solve. =)

@johnwelton2606 11 месяцев назад

13.05. First time I have beaten Mark's time by any significant amount although having the given 4's does help!!

@sterilized 11 месяцев назад

great video

@cecinkm 11 месяцев назад

wait mark i want to volunteer at the sudoku championships if i don’t have too much school work. would you ever consider a “meet and greet” i want a selfie 🙏🙏

@christianlett 11 месяцев назад

17:05 for me with a couple of interruptions from the kids. Missed the Y-wing, but got the solution by figuring out that r8c7 always was an 8. Not sure if that technique had a name or not, but happy to have found it!

@psymar 11 месяцев назад

I'm curious how you got that; I'm at that point (just found the y wing) and I don't see how to eliminate that cell being a 9.

@Raven-Creations 11 месяцев назад

That was amusing, after categorically stating that you never do puzzles with more than one solution. Actually, there was one puzzle on the channel which explicitly had two solutions, but I can't recall the details. You could spot the problem with that 38 cell by considering C6. It's effectively the same problem, but attacking it from the opposite direction. Had you transcribed the puzzle correctly, I don't believe the solve would have gone any differently, other than not ending up with a deadly pattern. It actually wasn't a bad puzzle up to the point it needed brute-forcing. The y-wing was perfectly acceptable, and if anything it improved the puzzle. I'm sure a human setter could have tweaked it slightly to have a more satisfying conclusion.

@MisterM2402 11 месяцев назад

7:47 for me. This was all straightforward sudoku, no fancy Y-wings or chains or anything like that that other people are commenting. Now I'm worried I messed up somewhere and got the solution by accident!

@jonotick 11 месяцев назад

Exactly! I finished in just over 10 minutes, watching football and not paying full attention. Pencil marked the hell out of it but it all seemed reasonably straightforward.

@davidh.4944 11 месяцев назад

24:49@#1533. I for one, enjoyed this one. Most of the solve flowed very smoothly, right up to a final deadlock. But from experience I know that that point is where you can often find y-wings and empty rectangles. I used the latter on 8s to break through and finish it off. I would've achieved a better time, however, if I had started with that digit instead of walking numerically up through the remaining candidates.

@stevesebzda570 11 месяцев назад

Where was the "Empty Rectangle?" (I just mentioned that yesterday or something - and the other person didn't answer , or didn't know) Where was that Empty Rectangle though? (Someone else said "swordfish on 8s," so maybe you meant that?) You spotted an Empty Rectangle though? Where? Thanks

@davidh.4944 11 месяцев назад

@@stevesebzda570 I don't remember exactly now, but it was the same elimination Mark made with the y-wing about halfway through his solve. If that cell contained an 8, it would have chained around through a pair of cells lower down, and made it impossible to place an 8 in box 3. Very often these patterns overlap, and the swordfish, ER, and y-wing are just three different ways to spot the same conflict. I personally find ERs to be the easiest to find, so I always look for them first.

@stevesebzda570 11 месяцев назад

@davidh.4944 I couldn't find it (the ER cell ). You said it was similar to the y-wing mark did in the middle of the solve. (An 8 somewhere chained down below preventing an 8 being in box3) Is the ER cell in box2 maybe? (An 8 somewhere in there would prevent an 8 in box3?) Box2 maybe?

@stevesebzda570 11 месяцев назад

@davidh.4944 I can't find it. Thanks anyway. Box2 though?

@bossdoorpodcast 11 месяцев назад

Jokes on you, I had fun solving this puzzle

@pauleaton9236 11 месяцев назад

Same technic for me as needed to colour 4s and 8s as well

@nosy-cat 11 месяцев назад

This was a fun video. I enjoyed the irony.

@georgewhyte7096 11 месяцев назад

That was more fun than expected. I do agree that computer generated puzzles are generally boring and a hard slog. But this one had x-wings and y-wings and no long bifurcation chains. Glad you corrected your mistake of solving a puzzle with two solutions and put up the correct version with a unique solution.

@peterwest7855 11 месяцев назад

I think you were too critical of this puzzle. I got stuck so watched the start of your video and so then bifurcated to a solve. I then watched the end of your video and realised I had missed the Y wing (which I find hard to spot), which is the key to the solution. Overall I did enjoy solving it!

@sethoflagos2880 11 месяцев назад

Very instructive! Since without the specified 4s you were able to reduce the puzzle to nine 4-8 doublets, does this imply that only one specified 4 or 8 in any position would guarantee a unique solution? If so, does the 2nd specified 4 make the puzzle 'overspecified' and guarantee either no solution or multiple solution paths?

@psymar 11 месяцев назад

No; if you have a puzzle with one solution and one solution path, then whichever digit would be found first you can add as a clue without changing that surely? On the other hand it's almost impossible for a classic sudiku not to have multiple solution paths, there's just so many techniques.

@bkaozzz 11 месяцев назад

I hate puzzles where I have to bifurcate, so I appreciate the channel so much! Thank you Mark for the amazing job you and Simon have been doing these past few years!

@inspiringsand123 11 месяцев назад

Let's Get Cracking: 07:50 And how about this video's Simarkisms?! Pencil Mark/mark: 7x (08:18, 08:23, 12:05, 12:14, 12:24, 12:43, 13:36) Ah: 4x (12:35, 13:14, 18:05, 22:35) Sorry: 3x (11:11, 15:35, 28:01) In Fact: 3x (15:35, 15:58, 17:57) Stuck: 2x (14:36, 16:06) Brilliant: 2x (06:23, 07:33) Break the Puzzle: 2x (21:36, 21:52) Elegant: 2x (05:23, 06:16) Shouting: 2x (12:01, 25:45) Goodness: 1x (19:24) Apologies: 1x (00:20) Missing Something: 1x (14:49) Hang On: 1x (18:05) Obviously: 1x (16:29) Progress: 1x (12:46) Most popular number(>9), digit and colour this video: Forty Eight (5 mentions) One (38 mentions) Purple (37 mentions) Antithesis Battles: Even (2) - Odd (1) Row (13) - Column (10) FAQ: Q1: You missed something! A1: That could very well be the case! Human speech can be hard to understand for computers like me! Point out the ones that I missed and maybe I'll learn! Q2: Can you do this for another channel? A2: I've been thinking about that and wrote some code to make that possible. Let me know which channel you think would be a good fit!

@jurjenvanderhoek316 11 месяцев назад

27:45 You just need to know where one of the missing 4's is located. The second one is redundant.

@bristolrovers27 11 месяцев назад

Looks like I guessed the 4 and 8 s in the correct positions !!!

@MattYDdraig 11 месяцев назад

10:01. I completely agree this was nothing like the usual fare here. Just a case of bashing the numbers in. So appreciative of the care and thought that goes into the crafted pieces usually showcased here. The Song of the Serpent earlier as an exceptional example of why those puzzles are thousands of times more fun than the generic computer puzzles.

@stephensanders5166 7 месяцев назад

Never realized my method of Sudoku was the Storm Trooper method. LOL

@remybeauchamp 11 месяцев назад

World Sudoku championships will be 6 hours away from my home but l'll be in Asia. Classic me 😂

@dcope4241 11 месяцев назад

7:52 for me; nice one!

@lizzzylavender 11 месяцев назад

I was SURE there must be a Y wing somewhere, but I just couldn’t begin to find it. I don’t know how you picked that out so easily haha

@Phil_Schaffer 11 месяцев назад

26:26 Would have probably been quicker if I had bifurcated earlier. Totally agree that computer generated puzzles are much less fun than the regular fare.

@kevinthurlow8055 11 месяцев назад

Slightly harsh description of Simon as "Mrs Rochester", who was the mad woman in the attic!

@shannonmarbut3648 10 месяцев назад

The thing about computer generated sudoku apps, is they have a solution in mind. So if you get to a place where you have 9 pairs of the same two digits you can still technically solve it. They just count your placement of ambiguous digits as a mistake if it's wrong, and you're only allowed 3 mistakes.

@nightwishlover8913 11 месяцев назад

I enjoyed solving this one - mainly because I did.

@awilliams1701 11 месяцев назад

Actually simon did a puzzle where it had 2 solutions and it was actually in the rules. lol Simon was supposed to get it down to where it's all solved except the deadly pattern. Personally I didn't care for that one.

@gregorysantos7624 11 месяцев назад

I didn't spot the Y-wing but even still I would have never been able to look ahead so many steps in column 6 to find that solve, even with the two given 4's.

@FrancisFjordCupola 11 месяцев назад

Technically it wasn't a puzzle with two possible solutions... as it was mistranscribed. Not the puzzle's fault really. Still fun watching it. I like to see normal sudoku's once in a while. Good explanations for techniques too.

@titusadduxas 11 месяцев назад

24:45 - Guessing a 4

@nikitashaitan9984 11 месяцев назад

Got it in 10:09 The puzzle was straightforward and i actually did find it to be enjoyable. Don’t see what’s the issue Now watching the video. I think i got is faster because i did not do coloring at all. No advanced techniques were mandatory here. It was all simple sudoku

@fatmanfalling 11 месяцев назад

I had to color and bifurcate to get the solution, but I spotted that Ywing and that made me happy

@Kirbyfan87827 11 месяцев назад

Finished in 17:45, and I had to trial and error the final logic chain, so you were right, I DIDN'T enjoy solving it.

@WeaselOnaStick 11 месяцев назад

I managed to do it in 18:50 but with error/pencilmark checks and lucky bifurcation as I'm still just a newbie 😅

@hom-sha-bom 11 месяцев назад

at 22:45 you say you don't like this solution because "it is a kind of look-ahead" but you guys do that in almost every single "hand crafted" sudoku puzzle that you solve on this channel. It just seems like you guys would call the exact same solve "gorgeous" in a puzzle made by clover or jay dyer or fistomefel or aad, but it's icky if its not made by them for some reason.

@gilleslesire4983 11 месяцев назад

At some point this puzzle needed a bit of brute forcing, which is not a strategy I like to use.

@psioniC_MS 11 месяцев назад

I'm curious to hear what's the easiest logical way to solve the final stage of this puzzle. @windchwang mentioned a swordfish on 8s which took me quite a while to spot in rows 2, 3, 5 and columns 3, 5, 9. Anything simpler?

@RichSmith77 11 месяцев назад

Is that a swordfish on 8s?r4c9 is also possible in those columns, and r3c1 in those rows, no? I'm not going to claim my way was simple, but this is what I eventually used: The 56 pair in c4. If r3c4 is a 6 it makes r4c1 an 8 which forces purple to be 4 in box 4. However, if r7c4 is a 6 it makes r7c6 a 4 which makes green be 8 in box 5. Either way, purple is 4 and green is 8. (It's really quite a long chain - I just chose to view it in two directions from the centre, to kid myself I was using shorter chains 🙂). Edit: That was on my solve that had the given 4s. Edit 2: Fixed a couple of cell references. (Thanks @psioniC_MS!)

@psioniC_MS 11 месяцев назад

@@RichSmith77 nice one! i think in your first case you mean r3c4 for the first position of the 6, and then r3c1 becomes an 8, forcing r4c2 to be purple. i'm not sure if what i found is called a "swordfish", but if you take all rows and columns where 8 only has 2 possible positions (5 in total), then you are left with 3 8s to place, but the only possible cells are r2c3, r2c5, r2c9, r3c3, r3c5, r5c3, r5c5, r5c9 (the intersections of rows 2, 3, 5 and columns 3, 5, 9 without r3c9). this rules out 8's from r3c1 and r4c9. I hope this logic is sound.

@RichSmith77 11 месяцев назад

@@psioniC_MS Thanks! I did indeed mess up my cell references. Sorry about that. You did well to decipher my meaning. I don't believe your logic on 8s holds up. I cannot see why the following wouldn't be a permitted distribution of all the 8s at this stage: Going column by column from 1 to 9, 8s could be placed in rows 3-7-5-9-2-6-8-1-4. This has an 8 in both r3c1 and r4c9.

@psioniC_MS 11 месяцев назад

@@RichSmith77 I guess I overlooked that possibility. I must have thought some cells aligned in a certain grid fashion, but one pair did actually not.

@RichSmith77 11 месяцев назад

@@psioniC_MS I replied to @windchang's original swordfish comment looking for further info. If there is one, it may come after further alternative progress. I don't see it emerge in Mark's or my solve paths.

@GeekRedux 11 месяцев назад

I think it's still fine to claim the *valid* puzzles you solve always have only one solution.

@joekerr3638 11 месяцев назад

Fairly easy if you know how to color.

@adrianhead6272 11 месяцев назад

Completed in 7m01s

@DeborahJLeslie 11 месяцев назад

I appreciated this video, not only its irony, but Mark's validation of not liking what I call "if/then" logic strings. Oh, and the coloring is very nice!

@MrCheminee 11 месяцев назад

00:16:34

@aberrant322 11 месяцев назад

Thanks for explaining. I was wondering what bifurcation was.

@TurquoizeGoldscraper 11 месяцев назад

17:18 for me - I had to bifurcate at the end.

@MichaelGreen831 11 месяцев назад

Click bate - but I'm sucked in! And dang it, but I plan to enjoy this puzzle.

@wanderlustwarrior 11 месяцев назад

22:48 for me. After I read the video description, I tried to do as much as I could without using the 4s, so I could get as close to the video (in my head) as possible.

@MohdShamlakh 10 месяцев назад

I solved it

@boydegg 11 месяцев назад

12:21!! :D

@awebmate 11 месяцев назад

Enjoyed both the video and the solve. I always solve the puzzle first to earn my shouting rights, so i didn't know it was computer-generated. Wasn't that bad. Not a worst case scenario.

@TheBeginningGuitar 11 месяцев назад

20:31 for me, no bifurcation. I agree, not the fun solve. I'm very glad that you usually use hand-crafted puzzles. This helps me remember why I appreciate the sudoku setters so much!! I have not seen the video solve yet, so don't know how Mark solved it, but I used a few finned X-wings, and a couple XY chains (at least that's what I've heard them called). Very tedious!

@stephenmccarthy1795 11 месяцев назад

I think that this is good puzzle to demonstrate the coloring technique. I don’t think that it can be solved otherwise.

@stephenmccarthy1795 11 месяцев назад

So Mark predicted that it would be solved by guess work, turned out not to be so with color.

@RichSmith77 11 месяцев назад

@@stephenmccarthy1795He still guessed whether r8c6 could be purple, and then discovered a reason it broke.

@Anne_Mahoney 11 месяцев назад

As the video started, I started mentally solving the puzzle on screen and quickly noticed there were neither 4s nor 8s in the grid -- which of course means it's not uniquely solvable as presented. I was quite reassured when we finally got to the card explaining the transcription error! An instructive video, even for a relatively experienced solver. I have nothing against computer-generated puzzles, and do the ones in my newspapers regularly, but they're the sudoku equivalent of cheap boxed red wine as opposed to a decent vintage bottle, of a fast-food burger as opposed to a steak, of over-sweet commercial cookies as opposed to what I'd bake myself. Better is better! 😼

@ianoz1 11 месяцев назад

Used the 4-less version... then coloured 468 triples... resolved uniquely once the colour of the 6 deduced.

@RichSmith77 11 месяцев назад

So, this would be the second puzzle published that has had two solitions. Anyone else remember the Hydra Sudoku? It had a unique placement of digits, but two possible snake paths. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xMO8_WN7v5g.htmlsi=Mx15MRAZXUJLH0zX

@bruceh8043 11 месяцев назад

I was slow and took me 29:03 to finish.

@RADZIO895 11 месяцев назад

13:39 for me

@essentialatom 11 месяцев назад

I think you're a bit unfair on this puzzle and in particular the criticism of the chain you used beginning in box 8. You had to notice that 48 pairs were showing up all over the place, you chose to colour them, you had an inkling about how picking one or the other would lead to a contradiction. I appreciate it's not sophisticated solving or a very smart trick, but it's not unreasonable to think that a human could, and would, as you did, work it out. I enjoyed this puzzle and I enjoyed the point at which I did something similar. I made the guess in the 468 triple in column 9 that I thought would have the biggest effect on the rest of the puzzle and most likely lead to a contradiction, and it did, which gave me the digits I needed to reach the solution. Yes, it's bifurcation, but I think the better your reasoning for making the guess, the clearer your expectations of what it'll show you, the more defensible it is, and it was fun to follow the chain of logic around the grid until the contradiction I expected to see materialised. It showed me I was right to expect it and that was satisfying.

@theredstoneengineer6934 3 месяца назад

16:50 for me

@Rach881101 11 месяцев назад

18:52 for me.

@andyhoudini 11 месяцев назад

Just over 10 minutes on my second go, messed up the first time and started again. I think the solve is a little easier with the given 4s. :D

@srwapo 11 месяцев назад

21:24, I had to guess at the final numbers, gonna watch the video to see the logic that I missed (and the HARDER solve!).

@joemucchiello4542 11 месяцев назад

9:33 and nary a color required. This seemed like a very straightforward sudoku. But the, the fours were with me.

@kwongshuchung 11 месяцев назад

35:25 for me @#2110

@j4v4x 11 месяцев назад

I used to enjoy bifurcating pencil puzzles because it gave me a chance to use my colored pencils. Now there are adult coloring books. I was way ahead of the times! 😂😂😂😂 Thanks for the explanations and for doing this exception video. ❤❤