Diabolical Sudoku Solving: Behold, Excalibur!

[@JasperJanssen]

“Which is... precisely no use at all.” Yes, that’s how I feel even when I solve regular sudokus.

[@Numberplay]

Needed it in the end. Or else there was not a bent triple.

[@shane8037]

I love when I'm cooking along wondering why a puzzle is so easy and then realize I goofed up somewhere ten minutes ago and have to restart. Really keeps the hubris in check. Guess I will remain a peasant for now.

[@Oblivion776]

If "King of England" isn't added to tomorrow's opening crawl as one of Simon's titles I am going to be sorely disappointed.

[@Pyromonkey83]

Man, every time I see Derek's name come up for the puzzle I shiver a bit, and this one was no different. 40 minutes for my solve time, a lot of which was me staring at the grid finding useless pairs (well, not useless, but didn't help me progress the solve until later) and ultimately going to full notation before I found the Y-wing and Empty Rectangle. I do love these challenging puzzles though, they REALLY test my solving skills, far beyond what I would otherwise find in most apps out there. In other news, I just completed the 40 puzzles in the Sandwich Sudoku app, and I must say you really ramped up the difficulty at the end! Puzzle 35 ended up being the hardest for me by far, followed by the last puzzle. My average solve time across all of them was about 20 minutes, with puzzle 40 clocking in at 58 minutes, and puzzle 35 taking me nearly 2 hours. I ended up having to bifurcate on puzzle 35 as well, and could never find a logical solution for it. I went back and checked the hints, and was confused as to how they supposedly solved the 1/9's, as I still couldn't see the pointed logic of them. Might send you an email on them later. Either way, the app has been brilliant, and I cant wait for more puzzles to come!

[@firemaker282]

at 3:36 the 5 in the bottom center box forces a 5 into the right box for row 9 leaving you a 6,3 pair in the two remaining squares in the bottom right box.

[@CrimmzZT]

imagine if he did a video where he just solved it like "ahh this must be a 8" without any little highlighty referances annouced aloud so we had no idea where hes gotten every bit of information and are left behind questioning everything like "is he right? where is that number coming from?" I mean obviously hes going to be right, but like I think it would be a funny april fools vid

[@weak_sauce_jerrylightbulb5723]

I'd dig it lol

[@yichen6313]

My breaking point is slightly different - at 16:11, look at the highlighted cells. If R6C1 is 3, R7C2 is 7 because of the right-hand side 3's. If R6C1 is 7, R7C2 is 7 again, so we can place 7 in that box. This avoids the empty-rectangle + Y-wing combo.

[@eternalblasphemy6526]

Mine was understanding that 7 could never force a 178 pair in the box 4, as it would've broken the puzzle whichever war you would've put it (c2r4, c2,r6,c3r6). This logic puts 7 in c1 in the middle left box (box 4) which helps unwinding the puzzle.

[@eternalblasphemy6526]

What stunned me the most is the fact that I was able to spot a hidden 12 pair in the r3 very early (12 could only go in r3c7, placign it in r3c8 would've resulted in r3c7 having no candidates, as it would've eliminated all the possible candidates for it: 4,5,6 and 9) and boy I was wrong when I thought that was helpful.

[@EndlessMystify]

56 minutes. Took me a lot longer, but pretty happy I managed to find and solve the bent tripple at 16:10 in the video on my own :-)

[@jonmac007]

I for once I did this puzzle with out needing the video for help. Took me over a painful hour, lol.

[@MoarRushPl0x]

36:51 to solve. The choices I made for the triples were correct on the first go. I just took a really long time scanning for a guaranteed number that never came.

[@davidh.4944]

58 minutes here. I first found the 678 triple in box 1, then that sneaky little empty rectangle in box 8, and finally (after a bit of hunting around) the Y wing. After that it was easy sailing. So essentially the same as Simon, albeit much slower. A tricky, but satisfying, little puzzle.

[@brucerose4383]

thought I kind of sort of found the bent triple and carefully removed a 3 from r6c9 .. and puzzle collapsed .. kind of lucky for me .. but this really underscores the meaning of the y-wing and why its valuable .. a very clear cut case ..

[@chaotix37]

I have no idea how the y wing work until I watched this video. Thanks and truly appreciated.

[@drengskap]

42:18 for me, but not using any special techniques, just standard elimination.

[@schrippe6870]

Great puzzle. Great solve.

[@jdyerjdyer]

Another blast from the past, but one I enjoyed! Sadly I could not see the Y-wing so I just bifurcated on the 3-6 pair in the bottom right instead. I need to learn the Y-wing. I tend to miss them every time they pop up.

[@ChessRabbitt]

The key for me was the hidden 5 in col 9, once I found that the puzzle broke for me. The number Simon got very early on. Good job.

[@Goryus]

When he found the empty rectangle and then declared it useless, my heart skipped

[@Wecoc1]

Nice puzzle! It wasn't useless because he needed it to properly use the Y-Wing afterwards ;) I noticed it can also be seen as an XY-chain (or maybe a W-Wing) too, which interacts with the 7s in box 4; doing that you don't need the HR anymore. (You can check that on Andrew Stuart's solver)

[@Goryus]

@@Wecoc1 Yes, both of those approaches also work. I found them when originally setting the puzzle, but was pretty sure Simon would find the Empty Rectangle and Y-Wing approach, which was the intended solution.

[@Wecoc1]

2:58 There's a Naked single in row 9 [r9c7 must be a 5] + Naked single in column 6 [r9c6 must be a 7], that solves row 9 directly plus some others, it would have been a shortcut to 8:52 in a few simple steps. There are a lot of Naked singles in this puzzle that could have been useful to spot earlier, but you found the important tricks (Hidden rectangle + Y-Wing) that crack the puzzle, so it's still a great solve nonetheless.

[@borristhebrave7496]

@qc1okay lol what?? The op commented 2 hours before you, bot

[@eireannsg]

3:25 Check this row...5 and 7...not much there. Guess the 7 in column 4 was too far away to spot.

[@lewiswegner2339]

46m 31sec... first time I've managed a WXYZ-like chain, bit different to the solver, I proved that r6c9 couldn't be a 3 because it breaks r7c1.... which after watching the video I realise is similar to how simon did it

[@pietndala7394]

1and 2 pair raw 3 columns 6&7, then home straight

[@sheboman19]

damn.. didnt see those nines at 4:08. got stuck at looking for that bottom left block 9. after that it went relatively easy (40min)

[@itamarolmert3549]

31:26 not bad for a supposedly "diabolical" sudoku! definitely not that hard, but hey, I'm improving!

[@ivansincic7304]

I got stuck at the point where you noticed the Y wing

[@TheUntamedNetwork]

How did you possibly not scream "Behold! Excalibur!" at the end of the solve???

[@RandomBurfness]

I did this using Derek's "inverted Y-Wing" technique.

[@megaminxpll]

Pretty easy one, used a W-wing on the 37 pairs (r6c1,r7c2) @ 8:52, to crack it wide open.

[@siggimund]

This is what I thought "Hmm, there's something fishy here,- Excalibur is not a saber. What kind of blade is it? hmm" and then wasted a lot of time trying to catch that non-existing red herring. 😅

[@wanderlustwarrior]

23:10 to solve. I need more practice.

[@ChessRabbitt]

Interesting, I solved differently but we both got there.

[@ifroad33]

8:20 how did he find that 1,2,3 pair?

[@mux1c]

cuz of the 1,2,3 on the top left square

[@ericveneto1593]

In box 4, he TWICE mentioned pencil marks he NEVER actually made!

[@Boy314]

is there a video that discusses examples of spotting y-wings/bent triples? i am baffled by how you spot them

[@KB9LAD]

Yes. Try this... kzbin.info/www/bejne/aV7JlKyOo9OSq6M I recommend watching all of Sudoku Swami's tutorials. The guy knows his stuff.

[@onestone9871]

I still don´t get it (my stupidity). I hope someone can explain this to me, after all the years, I wasn´t playing sudoku 4 years ago.. There can be a 3 in 4 cells in box 7, and in 3 cells in box 6. There can be a 3 in 4 cells in row 6. How can you decide, the way Simon does, to look at the specific cells he does.

[@Not3xactly]

Pretty tame by diabolical standards

[@filam7371]

56 minutes...I got stuck so I decided to watch the video. He found the bent triple (which I didn't) and everything fell into place after that...

[@niuniuch]

truly historic moment in this video. guess what it is :D

[@sunriselg]

I had to brute-force it at the end.

[@HeyThisIsBrian]

02:11:53 . Absolute garbage but my first Sudoku in a few years and probably my first of this difficulty. yay.

[@tommiller856]

Don't feel too bad, I got 1:49:58 and thats with 1 or 2 tips from the video when I got especially stuck for 20 minutes or so.

[@Blubb5000]

2 years, 11 months and 58 days? Not too bad. :-)

[@wbball15]

If you can't be the king of England at least be the king of the isle of man

[@marcpoulin57]

Right now, the video has 666 LIKES. Diabolical ;-)

[@tomekduresov706]

Damn, couldnt solve it without 1 guess, lets see how the master does it..

[@tomekduresov706]

3 months later I managed to solve it in 37 mins, so there is some progress.. lol

[@michaelevans5980]

Simon has really over-thought this puzzle, I feel. Its the first time I've been quicker (15:50)! Not really "diabolical" IMHO.

[@user-yz8wr8vb7f]

Yes, the empty rectangle and subsequent XY wing were a nice catch. But again, I'm not impressed with the Snyder notation, as it just clogs things up (although I'll admit it sometimes finds an X-wing). It's more efficient to search out the hidden/naked singles and doubles at the start.

[@ericveneto1593]

3 CANNONT be in R6C3!

[@Blubb5000]

ExQUALibur (Germans will understand)

[@Prince_Gub]

took me 1HR, 17MIN, 13SEC

[@abhijitjha9911]

Can't call it Diabolical. Solved it in 12 minutes.

[@BaseJumpLebanon]

Def not diabolical... solved it using basic methods Edit: i also did it on my phone and it took me just under 16 minutes