A 'Hard' Puzzle that is actually ... Hard

[@warehouse23]

Relieved at your verdict, had to give up on this one, found it impossible. Thanks to your channel I'm much better at spotting X-wings, pairs, or naked singles, but still struggle with finding the vital triples that NYT often throw around.

[@niklassoderberg2168]

Worst channel, i found you last night and love it. Now im tired at work. Thanks

[@jesperwillems_]

Mark saying “oops” when he makes a small mistake like the wrong pencil mark type is now officially my new favorite thing

[@brendanmorales4504]

Can you try and speed solve a NYT Hard puzzle for us? I think it would be really cool to see you crack a NYT Hard as fast as possible!

[@bristolrovers27]

Brendan Morales I agree an excellent idea

[@jamesois]

@Anifco67 It would be an impressive display of skill

[@tadperry1817]

@@jamesois Agreed.

[@brendanmorales4504]

@Anifco67 because I can solve a NYT Hard puzzle, but don't consider myself comparable in skill to a UK Sudoku champion.

[@billyoung8118]

I'm pretty sure if either of these guys did the playback speed of 2, it would still much longer of a video than how long it really takes them to solve one.

[@richpalmer7662]

Thanks - I tried this 3 ties and then watched your video. Finding the 3 - triples was the key. BTW - the 1-8-9 triple in column 9 reveals itself early and was a big help to breaking through. I truly have learned so much from you and Simon. Thank you for helping beginners like me. My average time on a NYT Hard is 48 min. To see you do it in under 15 is amazing.

[@DevilishlyDutch]

One day I’ll have the patience to spot those triples, but until then I’m stuck on these lol

[@thomaslong8401]

I finally found my first triple the other day. It was glorious! Keep trying.

[@ernestofante8609]

I obviously bifurcated and "solved" it in 29:21 Then I did it again trying to solve it logically... and finally spotted those triples and solved it in 44:56... you guys are changing my way of thinking... and I like it! Thanks a lot from the bottom of my heart!

[@RoninSan7]

This triple you mention are actually "257", "25" and "27"... The last one can't be a "5" because of the line. But it still works to rule out the "7" in the top, doesn't it? I didn't know this trick so I got stuck in this puzzle before watching the video. Nice one!

[@TheSlinkyConspiracy]

I love how your logic is allowing you to fill good chunk of puzzle simultaneously. I always find myself too rooted to the Snyder notation. Always focusing one set of number or one cell/row at a time. Still a long way to you master solvers!

[@SeaMooseSamwich]

50:30 with a little help from your video to spot the triples! It's not very good but a month ago I wouldn't have even gotten started. So glad I found this channel!

[@justinstoll817]

I have done my local sudoku for years just to exercise my brain. I just recently discovered your channel and have enjoyed these videos as well as the tips. You have opened a whole world of new sudoku to me. Thanks.

[@bristolrovers27]

Bought me down to earth after my (relatively) quick solve of the Simon did today , Miracle Sudoku, this floored me in the end

[@SubKontraBas]

Logically solved in 45 minutes. I tackle it every morning. It would be fun to see you try the NYT-hard as fast as you can.

[@NelielSugiura]

My mind is too stuck on the previous video's constraints; and mixed with you saying it is hard, I shall just watch.

[@barbaralevine9048]

I’ve been doing the daily ny times hard sudoku and it’s been getting easier. There’s an option to fill in all the possible candidates in the empty cells and I’ve been solving the puzzles by just looking at the patterns in the candidates, and not looking at or focusing on any of the givens. It’s been training my eyes to find the triples so I can eliminate numbers easily. I’ll never be as good as these guys but this has helped me to understand how to find the patterns in a normal solve now.

[@aligalad9907]

I am finding that I am getting better at solving after watching your guys at work. I have always been a ‘labourer’ at sudoku. I learning to look for wider connections and links. Brilliant channel. So glad I stumbled upon you.

[@stephenmcguigan5237]

1 hour on the dot (2am half asleep 😂). nice puzzle!!

[@adamheywood113]

Managed to complete the bottom-right box, and a few numbers dotted about here and there. Pencilled in all the "possibles" and then, from these, eliminated all the "impossibles". Reduced to a few pairs, there's a 4-6 pair in the bottom row to left for example, but by and large there's nothing more I can see that can be eliminated. Been at it for 30 mins.

[@readersrock101]

I seriously was about to email you guys a screenshot of this puzzle for help when I noticed you uploaded a video and the title caught my eye. Can't wait to watch and compare my logic side-by-side with you, Mark!

[@readersrock101]

I don't know if I should be disappointed or relieved that I hadn't even spotted the first triple...thank you Mark! Now I know the "trick" to these NYT hard puzzles I've been having trouble with.

[@jesperwillems_]

Petition for Mark to speedsolve a hard sudoku on camera/stream (while not commentating/explaining bc that slows him down obviously). I would really like to see how fast these guys can actually solves those puzzles

[@brucerose4383]

This is really hard .. the 9 that ultimately ends up going in r6c5 was my undoing .. and not just one time.. I spotted myself Mark's triple in the lower left and still went astray .. this was brutal .. hopefully learned something ..

[@Piatato]

I don't know many advanced techniques, and that has apparently forced me to become quite good at spotting triples. 😅 For once this hard sudoku went quite smoothly for me. Solved it in 22:17.

[@erickehr4475]

Tried to solve it entirely “logically “ (by which I mean if I could prove a contradiction in my head, I could discount that possibility). Took me just shy of 38:49. So a pretty tough one.

[@rayzer8449]

After the first triple is discovered, use the number 7 on row 4, this gets things moving nicely.

[@MidasStorm]

Screwed it up first try around. Started again from scratch and got it in 37:18 on the second try.

[@tinytuzi8167]

I know this will never happen but I kinda wish you guys would break a puzzle just to show us that you’re still human. 😂

[@florianw116]

Apparently that happens but isn't uploaded on the channel.

[@rogerstone3068]

@@florianw116 Well shame on them!

[@catharina9287]

This took me 32:30 Minutes with a small break and a few hints from you. Thank you!

[@himi9158]

Someday I'll get the triples but until then it's nice to keep seeing how they work. Thank you :)

[@alienrenders]

I only saw the middle row triple by accident. For me, it just helped restrict the other cells in the row and help finish off the box on the right. Then I spent half an hour stuck because I forgot to remove a 2 I had pencil marked. It resolved itself completely after that. Just under an hour because of that stupid 2.

[@Lord_Volkner]

Nice to have an easy relaxing puzzle now and then.

[@matthewjamestaylor]

I got to enjoy this puzzle for 90 minutes. But I did solve it. Thanks for sharing. Cheers.

[@imnoob92]

25:56. My method is just to put all the possible numbers in every cell when I am stuck and try to see if there's a double/triple/quadruple, and it happens.😅

[@luke8558]

I tried to solve it, was like 60% done and then accidentally reloaded the page -_-

[@brendabalzan1994]

I feel your pain. Filling half the cells then you reload by mistake, happens so often

[@kevray85]

I wish there was a way to keep it from doing that in safari

[@sunriselg]

18:05 for me. I immediately went into full notation. I had to do a lot of systematic searching.

[@JohnRandomness105]

9:20 The 19 gives another triple in box 6, 189.

[@DOSSTONED]

22.03min, actually list all candidates and use three subsets to remove extra candidates and go as normal. Finding the subset entertains a lot:)

[@deepanshushukla116]

I felt this puzzle was little bit easier if you pencil mark all the leftover blocks. I was easily able to see 257 triple in column1, 236 triple in row 5 and 189 triple in middle left most box. After that it wasn't that difficult.

[@dylburt49]

Could you possibly do a video where you try and solve a puzzle in tournament mode and then watch it back explaining moves?

[@Coyotek4]

27:28 but I missed the triples Mark found and ended up bifurcating the @#%$ out of this one. I take little pride in solving it, though in fact I did get there.

[@mindthegap9541]

Watching this then off to bed! Yep, I've set my lockdown clcok to this channel!

[@paljomania4281]

Like filling up sudokus but never done those without paper and pencil. Seems easier with computer. What is Cracking The Cryptic using?

[@tadperry1817]

There was an "easier" but similar logical path that didn't require much to see. Diligent penil marking an paying attention is all you need to get there. A slightly different "bent triple" mad of 235, 23, and 25 occurred in the first two columns at the bottom of Box 4. The 23 pair could never actually be be a two or no two was possible in the lower left box.

[@super_7710]

Stayed up until 2am trying to solve this. Didn't even know about the triples technique and couldn't even find them when I knew about them.

[@LednacekZ]

you missed the obvious 189 triple in the 9th column which would solve it much faster and do a triple in the middle right square

[@oNtuobAwoH]

This might be the first time I spotted all the necessary triples to solve the puzzle. Still took me 30+ minutes, though.

[@RealCadde]

I don't know if Mark spots this early on or not, i am solving the puzzle right now. But simply having read "New York Times" in the description, my eyes immediately focused on box 9. The 1258 there places those digits in row 7 in the other two boxes. As such, the only digits that can go in box 9 on row 7 are 479. The seven is placeable right away and then you get a 49 pair which resolves right away as well. Basically, New York Times is a one trick pony... Let's see if this one is as hard as the video says it is.

[@RealCadde]

Ok I give, this one is beyond me... As usual. I was so happy to have spotted the above so quickly and i worked away diligently on it until i got stuck for an hour and now i've given up. Must be something silly with this one.

[@dczzzz55]

Found two xwings on 1 placing a 1 in R1C5. Then the 257 triple opened up the rest

[@matthewwells649]

I don't understand the logic leap you took around the 6 min mark with the triple down the left. You seemed to forget about the 5's must be in the row 8 columns 5 or 6 which eliminates column 1 row 8. But at this point a 7 could still be in row 6 at column 3. It seems like a leap of faith that worked out in the end.

[@georgescoresby]

Thanks for the triple demo.

[@TheWhitePony83]

Took me over an hour, probably the hardest normal sudoku I've ever solved

[@user-kq3yz4be4h]

very nice, mark u r awesome

[@konte1995]

how can the 7 r1c2 be placed for sure when the 7 in bottom left square can also come in c3 and in middle left square can potentially come in the center?

[@xmadrugadaxeternax]

So many triples!

[@PSXMicha]

i never understand why 5:51 situations are a triple if the 7 can't go in the middle cell of the triple

[@midehv]

I'll try to explain and probably do a terrible job. A triple doesn't mean you have 3 cells that have all been constrained to the exact same three numbers (though that is possible). It means that across 3 cells you have determined that 3 different numbers need to appear there, in some order, to satisfy (in this case) the column. So a 7 being restricted from the middle cell limits the possible combinations of the triple, but doesn't change the fact that those three digits need to be in those three cells. As a check, try to place one of the digits outside the triple, perhaps a 7 in this case since it's the one not showing three times in the triple, and see if you can still satisfy the column. If you placed a 7 in the top left corner of the grid, you would reduce all 3 cells in the triple to 2 and 5. You can't possibly fill three cells with only 2 and 5. Hope this helps.

[@PSXMicha]

@@midehv Thx for explaining! yeah I totally missed the point that if the 7 goes into the upper left, than 3 cells have to filled by 2 and 5

[@odesseydekimola]

@@midehv Hi mate, i am sorry to bother you but can you explain me that while we decide that 3 purple cell is a triple, how can we eliminate the possibility that 5 might go into the cell at the left side of the "3" cell and 7 might go into the cell under the 3 cell inside that 3x3 grid so that we can say that this 3 purple cell is the only place that 2-5-7 can go? thanks in advance.

[@midehv]

@@odesseydekimola I think your question is in reference to the pencil marks. Remember that corner pencil marks suggest that those cells are possible locations for a number in a box, but center pencil marks are spots that HAVE to be one of the numbers marked. Note that by the end of the video the 5 ends up where you suggest that it can in box 7, but that't not the point of discovering the triple. In fact upon discovering the triple, he doesn't disambiguate the triple immediately or even after a while. He's just using that information to eliminate candidates in column 1. I suppose to answer your question, by finding a triple, all in column 1 in this case, he's not trying to find more information about box 7, he's noting that 2 5 and 7 can't appear elsewhere in column 1, notably a 7 in the top cell. At the 5:51 mark, take a look at what affects column 1 with the notations and not box 7. Edit: After reading your question again, I realize my answer was slightly off from what you were asking. You were asking how his constraints had any affect on where digits go in box 7. The answer is they don't. If you find a triple all in one row or one column, as in this case, those constraints are applied to the column.

[@odesseydekimola]

​@@midehv ​ Ok, ok this is cool. I am quite new in this channel and trying to solve hard sudokus so before your answer i really didnt know the differance between corner pencil marks and the middle pencil marks so thanks a lot for the clarification. And now after reading your explanation a few times and try to understand the situation in that moment of video i think i kinda got it. correct me if i am wrong. now we have 3 cells from top to bottom which can takes only thess numbers (2,5,7) (2,5) (2,7) we dont know which cells should get which number exactly for now, numbers can shift between these 3 cells but what we know is these 3 numbers have to be in these 3 cells and we use this info to determani the location of the 7 in the top left 3x3 grid. And that's super cool. very hard to spot for a beginner but very useful and i really appreciated your effort to make it clear for me. Thanks a lot mate. Have a nice day.

[@MichaelJPartyka]

If this is hard...then I'm actually getting *better* at this! WOO HOO!

[@randybartlett3042]

Great puzzle! Great solution!

[@DIPPY16]

6:16 I need further explanation. It just does not suit my observations. In Column 1 Row 8 we can already say it cannot be a 5 because 5 has to be in column 5 or 6 row 8. We cannot also predict that 7 will be in column 1 row 6 as it can also be in column 2 or 3 row 5 and 6... Moreover 2 cannot be placed in Column 1 Row 6 because it has to be placed in Column 8 Row 6 (from further solving, I went a little different way) How on the earth am I supposed to find that sort of hidden triple in sudoku? Especially since I have already removed some candidates due them cannot be placed in certain cells.. Can someone advise me on this ? I can also send a photo of my progress... so that someone explains to me what do I have to do further.

[@ernestofante8609]

We do not predict anything, we are just saying that in those 3 cells the ONLY possible candidates are 2,5 or 7... their exact position in the column, at this point isn't important, but we are sure that in those 3 cells there is a 2, a 5 and a 7 in any order. Those triples/quadruples are not easy to spot, but with alot of training and with time you will surely be able to find them.

[@DIPPY16]

@@ernestofante8609 Ok but this is just PREDICTION. I cannot say it the other way if you say: here, here and there can be 7. It's just a random shot. I am just saying that there were more cells where 7 could possibly appear. What if in the end 7 was not in the right position? Start again? You cannot just define 7 is going to be there.. It's still pure luck to me

[@ernestofante8609]

Wait, it's not random. We SURELY know that those 3 digits are somewhere in those three purple cells. We don't know their position yet, but in that column ( and only in that column ) we are sure that there are those 3 digits in those 3 purple cells. Yeah, maybe you can find that, for example, in column 1 you can put a 2 or a 7 in another cell, but when you realize that those three purple cells can ONLY contain the number 2, 5, 7 ( look closely at the rows pointing at those 3 purple cells ) the other 2's, 5's and 7's in the column are wrong. Have a look here imgur.com/a/G21idJM

[@DIPPY16]

@@ernestofante8609 Many thanks for image explanation. This makes things a lot easier to me.

[@gregorymorse8423]

Nice solve indeed. I wonder if any take on insane diabolical puzzles in which no logical technique beyond stuff like multichaining and nets (as a mere alternative to bifurcation) could be done? Some puzzles even good computer solvers cant do logically without a brute force step or two. Can a human solver crack them without bifurcation using pencil Mark's and arrows and the like? I cant crack Arto Inkalas absurd world hardest sudoku (the old or the even harder new one) logically but it would be brilliant to see even a preplanned solve of puzzles meant to be out of human reach

[@FirstLast-wr9mh]

just write any numbers you like, no-one will check

[@88KeysIdaho]

If I'm doing a Soduku in a newspaper available to others (breakroom, coffee shop), and I screw up the puzzle, I just fill in all the numbers to make it look like I completed it, lol

[@ledeej]

Probably overlooking something very foolish, but I don't see how the triplet solved the 7. If the 2 & 5 go in the two outer boxes of the purple row, the 7 can still fit the 1st row, right?

[@ernestofante8609]

Those purple cells contains the numbers 2, 5 and 7. We don't know the exact order of them, but those three numbers are there. Now look at the top left box, and ask yourself where you can put a 7... row 2 and 3 already contains a 7 and thanks to that triple you cannot put a 7 in column 1, row 1 , so the only place a 7 could go is the cell in column 2, row 1. I hope that was useful.

[@ledeej]

@@ernestofante8609Hi Ernesto, thanks for your reply. But the middle purple cell cannot contain a 7, right :). Since there is a 7 at the 9th column. Therefore, I believe we cannot determine the 7 yet. What am I missing??

[@ledeej]

Aaah nvm. The lowest purple one cannot be a 5. That explains the triplet. Thanks!

[@carlhausman8157]

31:15. One of these days I'll learn to see triples. Probably. I hope.

[@wgroenewald]

I see the videos have a link to the web version to play the puzzle, is there any page which lists all of these online puzzles on your website? Or an index of sorts?

[@davidh.4944]

Some fans recently set up a google doc catalogue for the channel. There's a link to it in the description box in newer videos.

[@swingardium706]

You appear to have uploaded this video twice :)

[@nekogod]

1:19:53 A tough one, but satisfying nonetheless

[@JarrettWilliams99]

31:40 crikey

[@GerritHaase]

11:38 why do you take the 2 out of col 7 row 5, I don't understand this.

[@GerritHaase]

... because it is a 3,6 pair

[@Novas12390]

I just tried the NYT online sudokus of today (11-5), the "easy" one was ... yeah.. easy. But I couldn't solve the "medium" and the "hard" ones. Maybe I am not focused because it is already 1:30 am of 11 May or I am missing some obvious logic. Please do a video about these ones, because I want to learn and get better at sudokus.

[@nigelm5777]

Sjoerd van Onzenoort Is this 10/5 NY time? 11/5 not published yet. The medium has 756 in the top line?

[@Novas12390]

I mean the sudokus of 11 May

[@martinarcher1503]

11m 35s - i don't get how the 2 is eliminated from the top left of box 6. Mark doesn't explain why the left column is limited to the 36 pair. Everything was easy from there to the finish for me so it felt like a cheat

[@andrewzmorris]

Both 3 and 6 are restricted to the same two squares. That means that they form a pair and those must both be in those two squares. Another way of thinking is imagine that the 2 *was* in the top-left cell - where would you place the 3 and the 6? There's only 1 square left for both of them.

[@hepenypacker]

@@andrewzmorris You're right. Had to go back and take a second look at it. Thank you

[@fanyaugusts9760]

11:39..why he changes the 236 by 36 and the 6 by 36?

[@fanyaugusts9760]

Got it

[@konte1995]

i don't understand that 1st triple. first, bottom of the triple can't be 5, middle one is 25, and top is 257 how is that a triple when a 7 can be placed in center square of the D-box also? and also the 5s from that triple , there are so many other spaces a 5 can go, how could he make it for sure? was he just lucky with that guess?

[@davidh.4944]

No, no guesswork involved at all. C1R678 must contain 2,5,7 in some order (none of them can contain 134689), therefore 257 can be eliminated from the rest of column one. The contents of any other box, row, or column are unrelated to that deduction. Three digits and three cells in one house, a classic naked triple.

[@gregbattis2385]

This was my birthday video and these dang triples :(

[@balajiob8744]

Sir Could not follow you Kindly use stick and point it on the number and explain

[@m.h.6470]

put the numbers in my self-made sudoku solver... took less than a second to solve the whole thing. That's why I dislike "default" sudoku: it is just rinse repeat of the same mechanics - so dumb, that a computer can solve it with a few simple rules implemented in code.

[@ZeroRyoko]

3 1/2 minutes into the video and he got further than I did in 2 1/2 hours before giving up! :/

[@KyRaiden]

Why is that a triple? I am shure you are right but Can you explin why is that?

[@chrisjpf33]

I actually solved this one by myself!!! It took me an hour and a half, but still. :-)

[@aochaichan321]

41:58... That took me so long.

[@kikam3506]

can you please confirm a question I have regarding the "check" algorithm you have on the website. Does it check the missing spot to make sure there are no mistakes or against the original puzzle? or both??

[@PH34RB]

It doesn't have a solution in memory, nor does it solve the puzzle. It just checks rows/columns/boxes for 1-9 arrangements, and points out repeats/missing squares. That makes it wonky at checking irregular sudoku and ones with special constraints.

[@luca6032]

Can confirm wath @PH34RB said

[@super_7710]

How is that a triple? The 2, 5 and 7 could go in other places of that column.

[@super_7710]

Oh I see. If 7 went at the top, it wouldn't work.

[@blandon93]

I put 7 in the middle of the central box instantly. Maybe it shall speed up things.

[@JeremyPeterson86]

Can anyone explain how those triples force the 2 below at @11:51?

[@JeremyPeterson86]

Maybe of note: His 9 note was incorrectly placed in row 3 I think?

[@RealCadde]

Why was this video uploaded twice with different thumbnails?

[@jbsoul4575]

I tried it 4 times until I gave up.

[@MRAROCKERDUDE]

I can't load the web app. Not sure why. Can't load it on safari or chrome. Have tried restarting computer and web browser multiple times.

[@stevewilliams1085]

Same here. Not only this puzzle either

[@stevewilliams1085]

And firefox

[@MRAROCKERDUDE]

@@stevewilliams1085 I thought it was just me

[@rogerstone3068]

Works reliably for me in Firefox.

[@scottleamy3224]

14:26 how did he realise that was a 2? You could argue the exact same logic for the 5 to go there instead

[@currentmood9568]

The tripple makes the 2 go into the vertical line and with the help of the other 2 you can place it right there where he did :)

[@Bwaffles_]

That's exactly where I got stuck too... no idea how that works.

[@danielles3841]

18:16 this was hard than I expected

[@Magister_Sibrandus]

50 minutes!

[@paulreader1777]

I'm still trying to hone my triple understanding and my scanning for naked singles is still woefully slow

[@rogerstone3068]

Look for the cells with few or no Snyder possible in.

[@paulreader1777]

@@rogerstone3068 Thanks

[@failogor1396]

What does bifocate mean?

[@rogerstone3068]

I'm assuming bifurcate is when you just guess one of a pair of possibilities - preferably choosing a pair which has a nice long trail of consequences - and either it works out, or it fails, in which case your first guess must be wrong, so it must be the other possible.

[@failogor1396]

@Roger Stone Ah! Thanks for both the explanation and the spelling correction! It's actually a technique I employ too often. Lol

[@MateoJH]

I thought you said it was going to be hard...

[@kevinsnyder4658]

47min. No help! I can’t even pinpoint the turning point. Guess I found a few triples, even a quadruple I think?

[@lmelior]

Yep, I used a 1479 quadruple in the left center box to resolve the 257 triple in column 1, because I missed some easier logic elsewhere. Definitely a roundabout way to solve it!

[@kierkegaard54]

34:43 to me

[@spinaple]

This took me an embarassingly long time (more than 1h oops) but I managed to do it without bifurcating at the very least!

[@tadperry1817]

It took me 8 hours, but I fell asleep half way through and finished the next morning. More than an hour of actual time if I'm honest though.

[@glum_hippo]

I''m the one who rescued this video from having 666 likes, by liking it.

[@pema22]

4 ppl can only solve 2x2 sudokus

[@BlackMorc]

10:27, easy but fun to solve!

[@r0bw00d]

HELP, PLEASE! I can't do triples to save my life. How do I look at something like this: i.postimg.cc/brDqysmN/Sudoku.png and know for a fact that I have a 238 triple on my hands? Since none of the numbers are restricted to those cells, I can't just kick out any of the other numbers.

[@AWildBard]

How do you know it's a triple? I don't think it is. Because, as you say, you can't rule out the 1 or 5. You could rule out the 5, if you get the first triple in this video, but you would still have an unknown 1.

[@r0bw00d]

Six months later, I'm able to solve the puzzle in 1:14:26. The triple in Row Five was a complete pain to find. I don't like puzzles like this.

[@honigschlecker1]

Missed the obvious... 3/6 pair in box 6. That's embarassing 🙄

[@remigregoire2219]

400th, p.s. I think you got lucky, it usually spots double uploads and doesn't give an id to the 2nd one. But I'll go out on a limb and say y preferred the first one.

[@arjanstoel]

3:19 haha 6 and 9