How To Sharpen Your Sudoku Skills

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4 жыл бұрын

Bonus Puzzle 12 is a Classic Sudoku from Dean Mayer. You can play it here:
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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.
Thank you for watching!
Simon and Mark

Пікірлер: 126

@jeffreyguilmot8772 4 жыл бұрын

Took me longer than 4h!! In my defense: I had some breaks (smoking) and disturbances (kids), it was my first time using pencil marks and I had never heard about X-wings. I was doing fine until the X-wings but had to watch your video until that part came up ) after that I could finish it all by myself! I'm so fucking proud even if my time is 10 times that of other commenters 😅

@catarinarodrigues6234 4 жыл бұрын

Wow! I wish I had the confidence to keep with it for that long!! 😮

@kamilbidzinski475 4 жыл бұрын

25:30. Really proud of myself, I never manage to find these large X-wings, and I got these two reasonably quickly!

@DougCube 4 жыл бұрын

On the reasoning of overlapping X-wings (starting 12:31)... Another way to explain it is that after clearing off the X-wing candidates, you look at row 5 and must have a hidden-pair of 12 there.

@chrisb8698 4 жыл бұрын

25:17, I feel like this would have taken me hours to solve this if I hadn't been following this channel for a few months now. Finally finding practical ways to apply advanced techniques and/or getting better at spotting when they apply. X wings, hidden pairs and singles, and other types of nonsense all included. Great puzzle!

@aniketb2010 2 жыл бұрын

NonSense .. 😉👍🏻

@Blindpig14 4 жыл бұрын

Wow...my favorite video! I now understand more about your approach to solving! PLEASE DO MORE LIKE THIS!

@toddschaefer5488 4 жыл бұрын

Fun puzzle. Getting better at spotting those patterns. I really appreciate the extra content and practice. Stay safe, guys.

@MythoFoxical 4 жыл бұрын

25:08 The first puzzle I attempted that I was able to do! Started watching this channel a few months ago because I enjoy Sudoku and only started trying these puzzles once this quarantine business started.

@nicoleleboeuf-little1048 3 жыл бұрын

I never spotted the X-wings, but solved it very quickly with pencil marks, bi-value cells, a few naked singles, and of course those 9s that suddenly come tumbling down. So I was really interested to see Simon go for the X-wings--and the added lesson about overlapping X-wings was really helpful!

@MarcosVinicius-so9tg 4 жыл бұрын

8:42: "Now: does that matter? I have no idea" LMAO

@danruley499 4 жыл бұрын

28:37 - mostly staring until I found the nice X-Wing pair and then things resolved themselves quite nicely! Great puzzle!

@dougmelven2597 4 жыл бұрын

Couldn't see either x-wing so I stared at the puzzle for a long time with nothing going in. Tried the slot machine on 9s, got nothing but the elimnation of 2 candidates. So I decided to watch the video for help after about 45 minutes with only 2 digits. Once Simon said to look at the columns that had the 1 x-wing I saw the x-wing on 2s and sailed home from there.

@maximinix 4 жыл бұрын

I would be very interested to know what your thinking was starting at 6:25, what lead to the 1 X-Wing. Once you show it, ok, everything becomes obvious, Were you looking for an X-Wing? If yes, was there a clue that told you "now it is time to look for that pattern", and what was that clue? Because you have to admit that the 1s in C8 are far from being easy to spot. I have the feeling that this untold part of thinking would sharpen our skills. Also the speed at which you saw the 2 X-Wing --- which is a symmetry of the 1 X-Wing --- lets me think there is something more to the story.

@eternalblasphemy6526 3 жыл бұрын

It took me forever to spot an x-wing on 1s (though I was able to find x-wings on both 2s and 3s pretty easy). If a puzzle is set like this (i.e. has numerous boxes filled with numbers that sort of go "through" the box (e.g. r1c1 r2c2 r3c3), it's almost 1 hundred percent you will have to look for x-wings (more often, swordfish patterns). Try Tattoine sudoku and you'll understand what I'm talking about.

@kathc349 4 жыл бұрын

These vids help me rewind my logic, I often instinctively know what number belongs in a square but when I try to unwrap the reasoning I can't, this helps me see what my brain has already seen.

@ardinrye4786 4 жыл бұрын

Man, I kept making mistakes on this one - largely tied to some incorrect assumptions that I've definitely learned not to do again. Having this video to reference to help me troubleshoot and eventually finish the puzzle was a huge help. Thank you for both the great puzzle and the help!

@travholt 4 жыл бұрын

45 minutes for me. Took me a while to find the X-wings, but I did, and for that I'm very proud of myself.

@emplore 3 жыл бұрын

Omg thanks to previously watching your xwing videos I was able to do this. I think it's the hardest sudoku I've ever done cause I've never used concepts like xwings before. Thanks Simon. 46mins!!

@gurrutvurstug8779 4 жыл бұрын

27:30, took me a little while to find the second X wing with the 2's. After that it wasn't too difficult

@cruisy82 4 жыл бұрын

23:41, that's pretty good for me. I seem to get better in spotting X-wings. Yippie!

@ShadowMark474 4 жыл бұрын

1:01:15 I feel like such an idiot, went around finding a ton of finned swordfish and x-wings and different elaborate chains to eliminate 1 or two candidates at a time, but overlooked one x-wing on 2's iirc that cracked the puzzle open that was staring me in the face for the longest time... Time to watch the video and see how easily Simon spots it lol

@shakiyadrayton5490 2 жыл бұрын

I’m super late to the CTC party, but I’ve finally solved a puzzle on my own and without breaking the puzzle at all! One of your videos came up randomly a few months ago and I’ve been hooked ever since. Your logic and strategies are effective and I’m learning all the time! This one took me 58:35 because I was moving slowly and kept double checking and second guessing myself. I’m really proud that I spotted the X-wings because I was struggling with that. Im looking forward to getting better and faster. Maybe one day I’ll be brave enough to try another kind of sudoku puzzle.

@rwind656 3 жыл бұрын

I forgot about overlapping x-wings. Either you or Mark have shown us that once before. Thanks. I was really stuck.

@DevilishlyDutch 4 жыл бұрын

I was so close to getting this one without help! I was looking for X-wings on 1s and actually found one half of it, but I didn't see its match in c2! Let alone the matching X-wing on the 2s that followed. Argh, ONE DAY!

@ryantamburrino3289 4 жыл бұрын

Really happy I found both of those X-Wings! Cheers Simon and Mark.

@MamselleManon 4 жыл бұрын

Not familiar with the X-wings so I followed along trying to resolve it with you and when this was done I continued by myself.. Definitely need to remember it, it seems extremely useful !

@azpcox 4 жыл бұрын

I always hate it when I find a digit or two before Simon on the video, but when working it out on my own I can’t see the x wings or even naked singles for several minutes. Thank you for the extra Isolation Puzzles!

@ziziorens348 2 жыл бұрын

I've spent more than an hour on this but man, was it satisfying at the end! First time I've had to use x-wings ever, and finding an actual factual naked single, which was VERY cool!

@stevesebzda570 4 жыл бұрын

Yes, enjoyed it. Nice pondering on the X-Wing and above. Cheers to you too 😆☕🍺

@LostMagyk 4 жыл бұрын

15:14 Found a "slot machine" pattern on 9s which wasn't overly useful, and then overlapping x-wings after looking and seeing 2s had a column restriction, then focusing on those columns saw the 1s were restricted too, which broke the puzzle for me. Pretty happy that I managed to see it on my own after struggling with some of the previous days.

@sebw89 4 жыл бұрын

24:19 for me. Has to be my fastest one yet, I guess... So proud of myself for spotting those X-wings ^^

@MyselfVlogsPaul 4 жыл бұрын

17:40. I sped up a lot once you mentioned the 2 x-wing because box 9 already restricted 2 into the bottom two squares from the other 2s, meaning because of the x-wing there was only one position, solving the x-wing.

@sunriselg 4 жыл бұрын

34:51 - Since these bonus puzzle were all pretty hard, I went into full pixel-notation after 2 minutes. That made finding the X-wings relatively easy.

@johnford3825 4 жыл бұрын

Love the background sounds. Could even hear a Yaffle (green woodpecker) calling at one point.

@ericveneto1593 4 жыл бұрын

Personally found it distracting

@dontwantid 4 жыл бұрын

Personally thought it was outside my house until I read this comment

@slimphotog 4 жыл бұрын

Solving a sudoku while identifying a bird in the background is high level cryptic cracking.

@nicoleleboeuf-little1048 3 жыл бұрын

OH IS THAT WHAT THAT WAS. I spent a few minutes wondering what insomniac bird is making that incessant two-tone racket outside my window at 2 AM? before I realized it was coming from my headphones and not outside in the Colorado night.

@RandomBurfness 4 жыл бұрын

A time of 14:29 for me! Luckily I remembered what it meant for two X-Wings to share a cell, which helped me quickly unravel the whole grid once I found the X-Wing on 1's and the X-Wing on 2's.

@TheMartyGangsta 4 жыл бұрын

21 minutes. I think this has been my best solve so far, it felt like it atleast

@richardfarrer5616 4 жыл бұрын

37:00 Found x-wings on 1s & 2s reasonably quickly (for me) but took a while to appreciate just what that meant for the middle row. Then just the usual slog of filling the rest in - always a bit longer than I would like.

@AractusPuphlicus 4 жыл бұрын

Wow that was so easy compared to the last one, I did it in 17 minutes. So straightforward, nothing complicated at all. I haven't watched Simon's solve yet.

@janozbolaz 4 жыл бұрын

20:47 oh, I'm starting to improve after watching and doing the sudokus on this channel for 6 months.

@thoperSought 4 жыл бұрын

thanks to some of your other videos, and Snyder notation, I saw the top x-wing, but I still missed the bottom one. def. a nice puzzle

@lukloberhofer6892 3 жыл бұрын

Thanks for those nice videos!

@BlueCyann 4 жыл бұрын

Took me longer to find the overlapping X-wings this time than the last, but at least I found them. Really quite a straightforward puzzle otherwise.

@luketurner314 4 жыл бұрын

41:14 Took me a while, but my time is a palindrome. I already got the 2 X-wing in columns 2 and 8 when I got stuck and started watching the video, so it combined nicely with the 1 X-wing in the video, which allowed me to finish solving

@PopeGoliath 4 жыл бұрын

It's very rare I see something before you do in a puzzle, so I don't have a lot of experience with the kind of patience being an observer requires. :) When you were working on 5s and got distracted by the X Wing resolution, I was softly cringing to myself as I realized the 5s could be finished off completely right then and there! Had to wait for you to cycle back around before my odd compulsion could settle itself.

@Peteybird111 4 жыл бұрын

Could you give an example of cracking a SUM-DOKU sometime. These usually stump me, and I'd love to see a technique for solving them. Always enjoy your videos. Peter

@NelielSugiura 4 жыл бұрын

Thank you so much for the video link when you mentioned the puzzle! Glad to have that reference. :D Got the two x-wings and remembered the trick related to them early on... but I keep failing to recognise numbers already in the same box, so I ended up with a BUG at 25min in. Restarted and after yet another fail for the same, got it after fifteen minutes... so forty total. I do not get why I am fine with numbers in rows and columns but boxes kill me. :(

@guricomfotodeanime9704 3 жыл бұрын

15:43 here, finally managed to notice an X-wing at a decent speed! Not on 1s though, mine was on 2s, in the same columns. Fun stuff!

@he1ar1 4 жыл бұрын

took me 20 minutes to place the second digit. And another 20 minutes or so to spot 2 x wing. Plus an additional 20 to finish the puzzle. 1 hour total

@chaotix37 4 жыл бұрын

21:39. The x wings really are hard to spot. On 2 and 1. They share at the same cell and row. That was fun

@woodchuk1 4 жыл бұрын

6:34. Had a little difficulty finding some X-wings, but that pretty much broke it wide open after I found them. Not a bad one!

@lakarto19 4 жыл бұрын

Nice bonus puzzle once more! I've commented this before, but again, I think it's never a bad idea to actively look for x-wings/swordfishes on seemingly 'symmetrical' (I know it's a pretty arbitrary definition) puzzles.

@claraklang376 4 жыл бұрын

you could have put down the 7 in box 7 like 15 mins earlier. Thank you for describing X-wings, I solved this puzzle without using it, but will def try to use it in the future:)

@ohiosucks2010 4 жыл бұрын

I hate how fast I got to both x wings because despite finding them my brain just completely missed their impact. I guess I am glad that I can finally spot them a lot better but I definitely need to improve on using their outcomes.

@blandingswest6560 4 жыл бұрын

Already at 8:46 you can place a 1 at r2c7 because of the X-Wing eliminations. However you neglect to do so for quite a while. Also, placing that 1 allows you to solve the X-Wing immediately. A missed early opportunity! In general you tend to switch to cell notation upon discovering X-Wings, whereas you would be better off sticking to standard (corner) notation until it yields no more results. This is perhaps the only obvious weakness in your technique.

@blandingswest6560 4 жыл бұрын

Oops, never mind! Actually the X-Wing (on 1's) does allow immediate corner pencil marking in block 3, but the solution at r2c7 comes only much later. I live in hope that one day I will spot something that Simon misses.

@generalmaximus4350 4 жыл бұрын

well done, I wouldn't have done that in a million years

@lemlem35 4 жыл бұрын

What a lovely puzzle

@Wouter10123 4 жыл бұрын

Holy shit, 14:05 for this one. That's even quicker than this video! Although I obviously didn't have to spend time explaining X-wings. Somehow, I spotted the two X-wings very quickly, which made the puzzle fall apart. Nice layout of the grid as well.

@SidawiKhaled 4 жыл бұрын

44:55 with your help (as usual) in X wing but it was fun!

@forkevbot 4 жыл бұрын

12:06 I gotta remember this important technique for when I am solving puzzles. 🤔🧐

@stevenlomon 4 жыл бұрын

Got the 4 in box 9 and found the 1 X-wing, then the pump was empty haha. But this video is extremely helpful!

@deleonmichaelr.2803 4 жыл бұрын

The x-wing technique is very helpful. Finished it in 18:13.

@DigitalizedArtist 4 жыл бұрын

Found the two X wings, put the 8 in and then, somehow got stuck since I didn't see the 4 that allowed me to place the 9 next to the 8. Opened youtube to see how you cracked it, and noticed the 4... Easy after that. I go fully blind when solving sometimes 😅

@LeCrenn 4 жыл бұрын

Found the x on the 2s pretty quickly, but spent a long time before getting the x on the 1s from Simon. That solved it.

@xaviarthunders4894 4 жыл бұрын

Thank you for the X-wing explanation, Simon. Much appreciated. I did find that this was solvable just with Snyder notations and wondering what mentally triggers you to switch mid-stream? Just curious :)

@bluerizlagirl 4 жыл бұрын

There's a fair bit you can solve just using pencil marks. And people talk a lot of nonsense about X-wings, making them out to be some form of black art or something when really, they aren't. The logic underlying X-wings can be got from first principles; as long as you can see two cells in the same row or column, exactly one of which must be some digit, you can eliminate that digit from _any_ other cell that sees them both, _even if it doesn't see any other copy of that digit._ It's really just the same as the logic where you can enter pencil marks for a digit into two cells in the _same_ row or column within a 3x3 box, and those pencil marks also eliminate that digit from the _rest_ of the row/column. The name "X-wing" makes it sound big and complicated and mysterious. It isn't. If in doubt, highlight cells that cannot possibly be a two (or whatever) by dint of sharing a row, column or 3x3 box; and if you can't see only one possibility for a two, look for either-or pairs where a two must go into exactly one of two cells. If you're really stuck, simply take a snapshot of the state of the grid and just flat-out _guess,_ filling in one or the other possibility. If you wind up with an impossible situation such as two twos facing each other, it simply means you guessed wrong; all you need to do is go back and fill in the other possibility. _You should never need to do this in real life._ A good puzzle setter will give you clues you can follow. (A computer algorithm that starts with a "solved" grid and takes away digits one at a time until it produces an unsolvable puzzle, then puts that last digit back, might well end up creating a puzzle that is mathematically solvable, but no fun.)

@StephanSpelde 4 жыл бұрын

Usually the trigger is when you see a digit can only go in 2 positions in either a row or a column. You then (should) automatically scan for a partner row or column to perhaps fit the same pattern. Sometimes it's not easy to spot the partner row or column, like in this puzzle, because the digits are not filled in, but just pencilmarked. In these handcrafted puzzles I usually am extra keen on the pencilmarks that are fairly easy to spot in the beginning of the puzzle as they often guide you to the next step.

@scwyldspirit 3 жыл бұрын

I was looking at the starting grid and noticed a pattern that if you look you see a diamond in the center and the 7's and 4's at the top. Not sure if they help to plan out the mappings in the other cells.

@goldenera7090 4 жыл бұрын

beautiful puzzle - i found the X wings on 1 & 2 earlier only bcos it reminded me of similar puzzle from Nikoli, i think, Kota Morinishi had solved a similar puzzle finding X wings first. perhaps i saw it on this channel as well.. Simon can confirm??

@goldenera7090 4 жыл бұрын

is it just me or people see some similarity with this other puzzle? kzfaq.info/get/bejne/fLOAhNdiu6vIpJ8.html

@bluerizlagirl 4 жыл бұрын

I ended up with a lot of pairs, then an "odd" pair turned up and resolved everything, one pair at a time!

@prahas777 4 жыл бұрын

That was basically how I got it. :-)

@howardtoob Жыл бұрын

I can't see how the column 7&9/box 9 restricts the 1s to only one cell? Seems like a 1 can also fit into R1/C7 no?

@prahas777 4 жыл бұрын

21 min. Just straight corner notation (with the relatively easy trick on the 3's). Sometimes simple is right! ;-)

@soyruba 4 жыл бұрын

16:34 yay! Binge watching tenths of videos on the channel since I discovered it is maybe starting to pay off! :)

@kareemelfarash4262 4 жыл бұрын

25 minutes, I'm so happy I could spot these 2 X-wings but not quickly enough though

@petzkuh 4 жыл бұрын

39:25. A bit slow, but I'm proud of finishing it!

@brucerose4383 4 жыл бұрын

Master's class on x-wings .. thx .. pretty hard ..

@LuisRivera-fx9wv 4 жыл бұрын

21:26 second puzzle completed out many 😂

@user-A168 4 жыл бұрын

Good

@wrebbitverifiedmercilessus7772 4 жыл бұрын

18 minutes. My thoughts on this sudoku: wow, just wow. Words are not powerful enough to describe how amazing it was to solve

@MichaelJPartyka 2 жыл бұрын

I DID IT! I DID IT ALL BY MYSELF!

@user-A168 4 жыл бұрын

Best

@GordonHugenay 4 жыл бұрын

yes, it took me 29 minutes. I believe that's the first time it took me less than twice as long as Simon.

@boydegg 4 жыл бұрын

Did it! 2 hours and 8 minutes. LOL!!

@insectbah 3 жыл бұрын

26:00 I'm really getting so much better!

@ethermelt4780 4 жыл бұрын

to my shock and fear, I found the overlapping X-wing faster than you! ...and then it still took me 31:29 to finish.

@micheltordoir7734 4 жыл бұрын

Ha ha... exactly the same happens to me, so happy to find very quickly the overlapping X-wing. Nevertheless unable to be quicker than Simon!

@UofMFan628 4 жыл бұрын

I'm still garbage at spotting x-wings, but at least I actually spotted them this puzzle.

@OrangeYoshi24 4 жыл бұрын

17:14

@awilliams1701 3 жыл бұрын

can I play along or is it blocked at work? Normally if it's blocked you get flat out told it's blocked........it looks like it's endlessly trying to load, but not actually coming up. I guess it's blocked. lol

@PSXMicha 4 жыл бұрын

why is that a 6 at 16:58?? where is the restriction? I don't see it

@glenntrav 3 жыл бұрын

I am confused as to how you identified the 2 x-wing.

@terryleddra1973 4 жыл бұрын

11:03 Nice puzzle but I did prefer yesterdays.

@aous9679 4 жыл бұрын

took me 39 mins :D

@Tommat194 3 жыл бұрын

I have a doubt that might sound incredibly stupid, hopefully someone can clear it up for me. At about 8:35, using the x-wing, he says "We can eliminate 1 from all of these squares", and then proceeds to highlight squares including R1C7,8,9. This led to my kneejerk reaction - working in tandem with the 1 in R3, we can immediately deduce that the 1 is at R2C7. At the end of the puzzle it turned out to be the correct answer, but I understand that he couldn't place it given that there was a possibility that a 1 laid in R1C8. That said, why did he highlight those squares as well? It appears to me to be slightly misleading, and since this whole idea of X-wings (and most advanced tech) is completely new to me, this experience is kind of making me question the usefulness of the technique.

@kamikazegargoyle 4 жыл бұрын

27:22 for me~

@RealCadde 4 жыл бұрын

I really don't get how to spot one of these. I mean, once spotted then the logic is simple. But to be able to see where the X-wings are... That's a whole other story.

@grailikegray1937 4 жыл бұрын

doosh, doosh, doosh 😄

@dannerino 2 жыл бұрын

I don't see how it is possible to spot that x wing on 2s so quickly and easily. There were 27 squares that could have been a 2. I highlighted them all and still didn't immediately see the x wing. How do you do it? Not only did you find that x wing needle in a boxed numerical haystack, you just happen to have marked c3r5 as only a 2 or an 8. So you find the camoflauged x wing and immediately see results from it. I don't know whether to be impressed or skeptical. (How the heck do you spell camoflauge?)

@howardtoob Жыл бұрын

What is that chirping sound?

@deepdarkmixes3589 4 жыл бұрын

15:53 without any x-wings)

@HiradC 4 жыл бұрын

Are they real birds in background?

@jamespants6591 4 жыл бұрын

15:16 Finish the 5s please... Got a bit overexcited with the x-Wing and completely misses it for 4 minutes... (Writes someone who completely missed the x-Wing for 15 minutes on his go...)

@msolec2000 4 жыл бұрын

On an unrelated note, how's this? (I don't do crosswords, and I'm not even a native English speaker, so probably not good, but what do you feel?) "Man standing within heart contraction is excessively prideful. (9)"