Simply Beautiful Sudoku Logic

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▶ABOUT US◀
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 eleven-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.
Thank you for watching!
Simon and Mark

Опубликовано:

18 сен 2019

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Комментарии : 132

@lauramcastro4897 4 года назад

What I find funny with these "you gotta spot THIS trick!" sudokus is that, by the time *I* spot the trick, I've pencilmarked the grid to hell and back. So whereas Simon spots it early and goes on at a regular pace, I slog for ages to find the trick, then shoot through the rest like a rocket because I've studied it so much by then xD

@RuneLar 4 года назад

You know things are about to get good when you hear: "Now, this is interesting."

@JohnJillky 4 года назад

And "oh this is beautiful"

@MrCharlieArgo 4 года назад

3:00 "umm..bluah...heh heh...uhh" *adjusts glasses, fidgets nervously* "hmm...OK..." same here, friend. same here

@rustysmith3565 4 года назад

OK, yeah after you explained i saw the logic [ after watching it four times ] but i don't think i'll ever spot something like that in my lifetime and how you spotted it so fast is astounding, miraculous, unbelievable, i can see why you're a champion, hell fire i'm stuck for words.

@kurzackd 2 года назад

so.... at what point does he actually explain the logic?

@skandinaviskman 6 месяцев назад

4:30@@kurzackd

@byoregon1 4 года назад

After watching you unravel that, I've decided to ask for my money back on my brain. I clearly got a factory second! I pretty quickly got the 23 pair, but that step you took to find the matching 23 pair would have eluded me forever. That was fun to watch - thx for these. This is such a fun channel!

@billyoung8118 4 года назад

It must be our name causing that? I keep thinking my skills are improving. And they have during the 2-3 weeks I've been watching these geniuses. But every time I get a bit cocky thinking "I got this..." I quickly find out I don't.

@byoregon1 4 года назад

Bill Young Boy was I confused at getting a reply from what looked to be myself!

@bailwrittepapichulo5623 2 года назад

I still don't understand how he got the first 23

@Wecoc1 4 года назад

In case someone was wondering what's the logic step behind the 23 parity, it's called a Continuous Nice Loop, and it's a kind of Multi-coloring. It doesn't only eliminate the other candidates (58) from r9c1 as Simon did, but also eliminates 23 from the cells in block 8 that aren't either in c6 or r9. They call them nice but I call them dope!

@jonmac007 3 года назад

Once you showed the 23 pair logic, I finish the rest of the puzzle without any help in 50 mins, A time I am proud of, LOL.

@johnnull1375 4 года назад

The 2,3 effect in column 6 also worked on row 9 in the bottom central 3x3 allowing pencil marking 2 and 3 into two spots, helped me immensely

@suburiboy 4 года назад

Just found the channel today and am loving it. I've loved pencil puzzles for years and i wish i knew how to find more. I can find a few books and sometimes can find a few online, but struggle to find enough to keep me happy.

@vickiastbury6758 4 года назад

Have you tried Conceptis Puzzles? They have puzzles on their websites and also have apps for Apple and Android devices. They release a free new puzzle every week, and there are also packs you can buy. Definitely worth looking into if you like logic puzzles.

@SlowJump1 4 года назад

I have never thought that i would enjoy this, But I did!

@keskinyavuz 4 года назад

I couldn't solve this without 23 trick and the rest was just average hard for me but I still came back to watch the rest of the video to make sure I'm not missing another trick like that. Great work Simon!

@lucasmandato4910 4 года назад

this one got me in a hard time!! a great hard time...thanks for it!!!

@carolaqalk5978 4 года назад

cool puzzle, impressive solving

@lawrencekallal6640 4 года назад

A very nice FT (forcing test) with the 23 to work out a solution path to this puzzle. Force testing or forcing chains are a kind of universal solution method that I resort to once I finish up with the usual suspect methods. Very effective for dealing with the most difficult puzzles when you can't spot things like a swordfish, bent triple or some of the more esoteric pattern.

@Pyromonkey83 4 года назад

Welp, that was a full hour before I completed this one, which I could only do by chaining (or, technically X-cycling, I think). Hudoku called the technique you described on the 2/3s a "continuous nice loop", which is one I've seen before, but never understood. Appreciate you bringing this to the channel, and I'll try to find more examples of these to practice with.

@AWildBard 3 года назад

That was amazing for sure.

@hotonis 4 года назад

Wow, that was really slick. That continuous nice loop. I gotta remember to look for those. That is crazy hard to find.

@colereynolds6892 3 года назад

Finally found a puzzle on this channel that I could do! Took a lot longer and a lot more pencil markings but it all looks the same in the end!

@fmakofmako 4 года назад

Amazing.

@JustFun-iz9rf 4 года назад

I tried it and could not get off the ground. Respect to you

@benharris3285 4 года назад

Took me 57 mins to solve but this was one of my favourite puzzles I've done so far!

@binarybox.binarybox 3 года назад

I was very pleased to have finished it in 40 minutes. If I get say a 2 and a 3 and another 2 and a 3, I try one way and then the next possibility if that failed. It's easy to backtrack on a PC but more care needed using a pencil. I used to go 3 levels down using the PC when guessing on difficult ones.

@BlueCyann 4 года назад

I came so close to understanding that 23 pair on my own (after a long time) but couldn't quite get there. But I guess that's why you're so good at this and I use hours and brute force.

@Czeckie 4 года назад

the 23 parity pair was huge deal

@jdyerjdyer 3 года назад

I know this puzzle is from a year ago, but it's new to me! Very nice opening. I didn't see it. I looked all over for pairs, triples, even quads and x-wings, but found nothing to break it open. Good spot!

@jamessweatt985 3 года назад

I found a finned X-wing (I think), but it didn't help enough. That one trick of Simon's, along with getting the pair in the first box broke it open.

@zen_art_of_guardian_sudoku 3 года назад

That was a nicely designed grid, elegantly solved.

@no-feetmcgee5577 4 года назад

Over two hours, three empty rectangles, and seven colors later, I've pencil-marked everything I can deduce and still haven't placed a single digit in the grid. I'm officially giving up, and can't wait to see what I missed that Simon probably spotted right away.

@no-feetmcgee5577 4 года назад

Wow, yeah, I was looking for small chains like that but never found that one. Kudos to Simon.

@sebastiaanb2651 4 года назад

@@no-feetmcgee5577 Same thing here. Also had a finned x-wing. I ended up just 'guessing' 2-3x (with 1 wrong one) and ended up solving it that way.

@rgpmtori 4 года назад

This was probably a poor Idea to try as my first sudoku

@markwilding3828 4 года назад

hahaha... Yes i think so.

@brucetimmins2514 4 года назад

That is certain.

@lsmart 3 года назад

Which reminds me, I haven't seen "Airplane" in a long while.

@billiardsprofessor 4 года назад

That was very cool. But, how did you spot it? Can you break down just what it was that made you see that?

@lsmart 3 года назад

From my observing experience, whenever there are no simple steps left, and the puzzle is still relatively empty, he either scours the fuller rows and columns for a cell that might be a pair or a naked single (which got the 2-3 pair here), or for a triple that might restrict the other cells in a row or column (none obvious here), or for the same set of numbers in several locations that might restrict certain cells when crossing each other from the columns and rows. Therefore, at the 4:00 mark, as soon as the check of column 6 (and the many different numbers crossing it in row 5) yielded the 2-3 pair, and he saw the 2 and 3 in the top-center grid, and the corresponding one in the bottom-right grid, he noticed the special symmetry with the r9c1 cell. I could not see that myself. But when he said, "Do have a look at what I might have spotted," I froze the video and found the trick.

@aniketb2010 2 года назад

All Hail ‘The Hell of a Puzzle’. 👍🏻

@jm184 3 года назад

Very happy with 22 minutes using just Snyder notation and standard sudoku rules. Didn't see that 2-3 logic and probably never would!

@theblackswan84 2 года назад

i tried it myself and very quickly was able to spot the "2-3" pair in row 5 in the middle box. unfortunately i wasn't able to notice the interaction with the other 2 and 3 digits in other boxes and got stuck instantly. it was painful to see you solve it so quickly :)

@joseffestejo7327 4 года назад

that 23 in column 1 row 9 was definitely the key

@woowooNeedsFaith 4 года назад

2:18 You missed two pairs of sixes at the bottom two squares. (Like it would matter. It doesn't look like it could be in any help at 11:11.) - It took me over 1.5 hours to complete the puzzle - but for that I needed your 2-3 crazy pairs to get forward.

@mauer1 3 года назад

i got it in around an hour. but it seems I got lucky at the start. I somehow got the 8 in box 2 as my first digit which gave me the 2 in box 3 and the 1 in box 5.

@davidorr6627 3 года назад

27:07 without spotting the 23 possibility in the bottom left. I'm quite pleased with that.

@longboren 4 года назад

Much clearer explanation than usual. Thank you!

@erichjelmfelt190 4 года назад

As to trolling, this looks like it might have been a "between 1 and 9" Sandwich Sudoku, that we enter into most of the way through the first part. I checked to see if it might have been one from their app, but I didn't find it. Perhaps this was from an earlier video.

@remigregoire2219 4 года назад

Just fyi, you have to hit hint 11 or 12 times in a row in Duncan's solver before you get the first number. Graded 89 and somehow feels harder than the ±110 "Slightly daunting" you did a while back.

@remigregoire2219 4 года назад

That 45 pair in block 9 brings it down to lvl 15 and somehow still needed another hint to finish :-).

@mikeparker3865 2 года назад

Loved the solve. I missed the 2 3 trick completely.

@balthazarbeutelwolf9097 3 года назад

I don't think Simon missed anything. I got stuck, watched the video, and then I saw Simon find that 23 pair in the bottom left. I resumed the puzzle and could solve it from there, pretty much the same way Simon did. But that 23 pair was tricky to spot.

@jamessweatt985 3 года назад

Same here. But the next find that broke it open (pair in the 1st box) took me several more minutes and took Simon mere seconds.

@paulreader1777 4 года назад

The 8 and 9 in the bottom left block resolved immediately you had established the 39 pairs because of the restriction on 9s in the bottom right block. I don't know if that would have made the solution faster.

@Tehom1 4 года назад

For such an easy-looking puzzle, this was quite hard. I did not spot Simon's {2,3} trick, but I solved it with a lucky bifurcation.

@ol1ver49 4 года назад

I can't believe how differently I did this puzzle. I didn't need to find that 23 pair, but I found a quadruple and quintuple early on, and the 2 top right was almost my first digit. I don't think I cheated, but needed less elaborate logic.

@djmiller232 4 года назад

It took me 35 minutes. I made a lucky guess on a 2-3 pair and completed the puzzle. Had I guessed wrong, I'd have had to undo the whole thing and start over. 90% luck, 10% skill, unlike Mark and Simon.

@nigelm5777 4 года назад

I don’t think you missed anything. Computer solvers first significant steps are two X-cycles on 2 then 3.

@massecl 4 года назад

Good computer solvers use only a tree, just sorting the branches. Indeed, you can find the solution still faster by simply writing all the possibilities in the squares. Now there is a square with only two possibilities, perhaps the 23 one. It is easy by try and error or reasoning to find which is correct, then the solution follows.

@serenity327 4 года назад

took two hours to solve, with multiple resets to match your grid. I seem to make simple mistakes and catch it when the grid is almost complete :*(

@tadperry1817 4 года назад

Me, too. Exactly the same problem, and it happens to me even after reminding myself to check every step twice (and sometimes three times) as I make it! I don't know what's wrong with me. It's something kind of like dyslexia. When I "unwind" the related pairs, I will sometimes get it backwards and put it in backwards and not notice until much farther down the line.

@PH34RB 4 года назад

@@tadperry1817 I find that I often corner-pencil-mark wrongly on squares where I was thinking of a digit and a row, but it's restricted column-wise, or vice-versa. I think it's part of the naked single learning curve: we start looking up and down and across and in the box, and fumble mixing the 3 concepts.

@mydoggylives Год назад

12:27... You would actually have spotted the 3/9 in R8C6 earlier if you'd continued down the Column when you got the 2/3 in R5C6. That's when I saw it. That being said... you're still the master because I never would've spotted that 2/3 parity you did (allowing you to get the other 3/9 Matching Pair)..

@hariman7727 4 года назад

Thirty seven minutes, seven seconds. Another Sudoku completed without help, and this time, 100% without help. I'm slowly getting the hang of this. :) Edit: I went through different logic, and I believe I got more of the upper area of the grid earlier. I didn't get trolled the same way, but it was still a challenge.

@valeckseimu3132 4 года назад

9:10 I found the 7 in the 2nd box BECAUSE 7 can only be in the bottom of the 3rd box cause 3/4 pair in the middle THEN the 7 in the 7 in the second box can only be in the middle With the 2 n 6 ... I feel so smart After he do all the work for me LOL

@hartosaarinen221 4 года назад

There is no 3/4 pair in the middle of the 3rd box. The four can also go into the bottom left corner of the 3rd box.

@RO8s 3 года назад

I had this beaten all alone, and then, not understanding the software, pressed the "check" button just before the end. It said, "That doesn't look right!" Oh no! I thought, I've made a mistake! I tried to "undo" until I could find the mistake, and went back and back and checked and checked. Finally I reset and put in my first number, checked and it said the same. I realised that the software only checks the final result and started again, but my confidence was so destroyed that I couldn't do it again. *Despair*.

@04LightningFan 4 года назад

When I woke up this morning, I realized I saw everything I needed to find the connection between R5C6 and R9C1, but I never put it together. I saw that both 2 & 3 were limited to just two cells in column 6 and that there was an empty rectangle for both in the bottom left block that allowed me to eliminate 2 & 3 from several cells. It like I couldn't see the forest for all the trees in front of me. Stared at this puzzle for 15 minutes last night looking for a pattern in the puzzle to find the troll, nothing. Then this morning, I got it. Very funny Harry. It's more fun to find on your own. The shorten form of my hint is look at the title 0:01 , sometimes it's a nickname for the fifth company in an army regiment, then realize what was Simon talking about when he noticed it. It's also the only logic talked about in the comments. You might need to squint your eyes to see it. Amazing how much better your mind works with a good sleep.

@dustingoodwin15 4 года назад

Very nice. Standard expert puzzle on the sudoku app I use.

@kristofersokk1580 4 года назад

A typical Schrödinger's Cell, but I have no idea how he managed to spot it so fast

@brucetimmins2514 4 года назад

I think the 2-3 in the lower right box deflected the 2-3 along the bottom row.

@asamirid 7 месяцев назад

i hope anyone explain more about what happened in min 4:00 .. how he restrict the cell in the middle box to 2,3 only?? what is this trick or technique called ??

@robertotomas 4 года назад

How d you get the 2-3 restriction in the center at about 4:00?

@ineedavacationbadly 4 года назад

The row has 1,4,5,9 in it and the column has 4,8,6,7.

@brianrichter8255 4 года назад

I even had the 2-3 pair, but just could not see the logic leading to the 2-3 in the corner. I started to watch the video, and then paused to see if I could figure out why he was being trolled (maybe the puzzle was impossible for some reason?). Being also stumped on that, I watched more of the video up to getting the 2-3 in the corner. Then I paused the video again and after seeing that first digit (5), found the rest of the solve straightforward.

@mauer1 3 года назад

okey i got it, but when im rewind, I now think, that i got a lucky guess in the beginning. I somehow got an 8 in the first row over the 2 as my first number. Now I cant think of any logic that let me think that cell had to be an 8. I think i overlooked the possibility of a 1 in that cell and thought it was just a naked single. btw if you know there is an 8 the upper right corner becomes a 2. just giving you the 23 pair in box 6.

@Fogmeister 4 года назад

Damn, thought I had it but got messed up with the 3s and 8s at the end. 😔

@VectorJW9260 3 года назад

me too

@seanm3189 3 года назад

Okay. This puzzle took me 3 hours. I feel like most of them do. I keep going until I see something because I hate just guessing. Everyone in the comments is always writing, "took me 20 minutes, but I did see yatta yatta so it took me way too long." Guess I suck at sudoku

@LTBComputers 4 года назад

at 12:3 how do you know thats a 6? couldn't it also be the top corner of that box? Im missing a piece of logic

@steverpcb 4 года назад

Yes snider notation would give the option for the 6 top left, but the only options for the square were 369, the 39 pairs eliminated them leaving the only option to be the 6.

@M4ke4l 4 года назад

That square is a 3, a 6 or a 9, If you look at R9C5 and R8C6 they both can only be a 3 or 9, that means every other squares in their 3x3 block can't be 3 or 9. so the only digit possible left is 6.

@ErwinRommy 4 года назад

Yah elimination. Makes sense.

@cbesthelper404 2 года назад

6 mins 31 sec. This was a friendly one.

@Tehom1 4 года назад

Waiting to learn why this was a troll puzzle. Besides "harder than it looks", obviously.

@danielwebb1645 4 года назад

He said it was sent to him advertised as an "easy" puzzle.

@eljee102 4 года назад

Correct me if i'm wrong but this puzzle doesn't have a unique solution. The 7-8 pairs in columns 7 and 9 indicate that the puzzle can be solved with 7 and 8 in either position in those columns. Try switching the 8 and 7 in each box on the grid. The puzzle does not break.

@bensonburner13 4 года назад

@@eljee102 I don't think so because in box 9 they're offset. If both sets of pairs were columns 7/9 and rows 3/7 then yes it would be 2 x-wings and could be switched. Becuase the pair in box 9 is in 2 separate rows it isn't broken since it affects box 7

@eljee102 4 года назад

@@bensonburner13 yeah you're right, my mistake.

@johnevans6414 4 года назад

Solved it in 18:09!! xD

@johnevans6414 4 года назад

I've learned a lot about naked singles. Maybe my logic is flawed, but i've used this method in other sudokus If I recall correctly, I rule out the majority of digits in a square and usually there are 2 digits left, for example lets say an 8 and a 7 in the bottom row are the least limited pairs of numbers in the bottom right box. Now what I did was the empty square I noted an 8 and then looked at the 7's and showed only 3 possible locations for 7's. Everytime I spot something like this, I basically take the invisible lock and put the 8 into the cell thus limiting the 7 to only 2 possible locations stacked with the other numbers in turn creating sort of a massive turn over. once you have the 8 placed in the imaginary cell you begin to unfold the rest of the puzzle putting in and filling out the rest of the least known digit. The puzzle will unravel at this point as it becomes more of a medium difficulty puzzle rather than a hard or an easy rather than a medium. it's something i've tested at least 8 times without fail, give it a try it might improve speedruns!

@spinaple 4 года назад

A good sudoku to relax, solved it in 10:28 ~

@SaneShenanigans 4 года назад

What makes this a troll puzzle? I’m fairly new to sudoku, so I didn’t understand why it was considered a troll puzzle.

@rilian226 4 года назад

I'm curious too... no idea why he thinks he was being trolled...

@stlrnk 4 года назад

@@rilian226 You can't put even a single digit in using usual tricks. You need to see this crazy restricted square.

@JohnJillky 4 года назад

@@stlrnk Now I'm wondering if that was the only way to solve it

@FazalFariz 4 года назад

It was sent to him saying it was an easy puzzle, believing that he was trolled.

@ChilapaOfTheAmazons 3 года назад

@@JohnJillky it wasn't the only way to solve it (you can always solve any valid sudoku using backtracking, aka bifurcation) but it was definitely the fastest way to do it. I didn't notice the 23 thingy and it took me an hour and a half to complete it.

@sannedg4293 2 года назад

I'm trying this puzzle as we speak. 1,5 hours in and I've not been able to place a single digit...

@bristolrovers27 4 года назад

The fact that I think you missed nothing means very little but I could be right

@markwilding3828 4 года назад

This brain solving newspaper puzzles... could be solving cold case crimes. it's Sherlock Holmes

@JohnRandomness105 2 года назад

Trolled: was it because of the corner 23-pair?

@Martiesim 4 года назад

Hi, this might sound weird but could you add the "y" key to your websites controls? Make it behave exactly the same as the "z" key. I'm german and I'm using a german keyboard so (among other things) the "z" and "y" keys are switched which makes the standard keys a little uncomfortable to use. Thanks :)

@razvystegarul 4 года назад

You can change the language of your keybord every time when you play sudoku by a simple click on the regional settings menu 😁

@xboxalaswad 4 года назад

Took me 22 minutes and 46 seconds.

@pietndala7394 4 года назад

That was hard...

@TheErusPrime 4 года назад

I thought I was gonna beat you on this one. I was able to unwind most of the top and felt like I was miles ahead and then you just start throwing out "that's a #" left and right and I end up about 5 minutes after the video ends.

@paultjee3073 4 года назад

@7:22 why couldnt it be an 8? Am I missing something?

@MoarRushPl0x 4 года назад

Nothing prevented an eight from being there; however, it was the only spot a five could go. Once he restricted the bottom left corner to a two or a three, five couldn't go anywhere in the bottom row besides the spot he put it.

@JohnJillky 4 года назад

To put it another way, if the 5 was in the other spot (test it yourself), the only place a 5 could go would be the bottom right spot... except we already knew this spot had to be a 2 or a 3, nothing else

@paultjee3073 4 года назад

@@JohnJillky thank you both! This whole clearing session went pretty fast for me because I used to do sodokus at beginner level and just "normal" sodoku techniques. I am going to watch it again soon and see if I understand now. Thanks again for the explanation.

@eireannsg 4 года назад

For the Sudokus I buy at my place in form of booklets Logic like Unique rectangle logic doesnt work. Sometimes having a unique rectangle with e.g. 2,6 as possibles in all four corners just gives two possible solutions. Eliminating 2 and 6 from one cell would result in an impossible Sudoku.

@msolec2000 4 года назад

So, what is the trolling?

@scragar 4 года назад

It's described as being fairly simple, but it needs advanced tricks or experimenting to even get started. No one would call this simple.

@hariman7727 4 года назад

@@scragar ironically, I'm a Sudoku novice, and yet I used a combination of row/column logic, pairs, and a few other signposts to complete this puzzle. I didn't solve it the same way either, but starting was the hardest part. The further I got in, the easier it became.

@Goryus 4 года назад

About 15 minutes for me on this one.

@Goryus 4 года назад

@@qc1okay I did and I didn't guess. Actual time on the clock at the end of the puzzle was 15:09, and that's actually a little slow for me for a puzzle like this. As to how I did it I approached the solve, I've gotten very good at spotting X-cycle patterns, and that was the first thing I looked for.

@Pyromonkey83 4 года назад

@@qc1okay You realize you are talking to the guy that solves insane level sudokus daily (and pretty much exclusively) and came up with the "slot machine" technique they put on the channel earlier, right? Derek is one of the few people I consider a sudoku genius, not in terms of a "speed solver", but in terms of the kind of guy that can do extremely advanced techniques in his sleep, and never needs to guess.

@jurgenkloppshead8373 4 года назад

Not many people have the credentials to make this statement believable. You have shattered my world champion aspirations.

@boydegg 4 года назад

Nope. This one's beyond me. tried it 3 times with clues from vid and still can't get it!!

@kurzackd 2 года назад

Then at 15:16 - "I can now place the 5 because of the pencil marks..." .... ummm... no? You can place it simply because of Sudoku... This isn't very serious, nor professional...

@jbruuuu 2 года назад

He is referring to the 5s pencil marked input the corners which is “by sudoku” I don’t understand what your first question is referring to

@sebastiantopel746 2 года назад

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-FVW2a42vRu0.html I dont understand how you can be certain that its a 6. top left corner in that square could also be a 6. Lucky guess or am I missing something??

@razvystegarul 4 года назад

I wanna see how you solve this puzzle on the sheet, with a pen. Sorry, but what you've done here is more mechanic than logical. Of course, it is your logic, but the logic was memorize by a soft, a computer. I solve these kind of puzzles on a sheet, very hard and took me around 2 hours. Sorry for my poor english, but i hope you understood me.