Thank you so much Simon. I was too busy making pencil marks and trying to look around the grid for chains because I fully notated the whole puzzle. After you filled in the center box is where I hit the brick wall. Your bent triple to determine the location of the 7 and 9 was a very nice find. I couldn't find it because all of the pairs in the grid sent me on a dumb chains hunt. I feel somewhat dumb right now but I certainly am not anywhere near the solver that you are. Thank you so much for doing this for me.
don't worry bud, i got stuck aswell at the empty rectangle step! i even looked around for empty rectangles & Y-wings, but i guess i haven't solved enough puzzles with such patterns to be able to recognize those patterns quickly enough. :)
Such a good payoff. I was stuck at that precise spot, deduced further from the 79 pair correlation and everything else fell into place. Awesome spot on the bent triple, too. It's just so rewarding to know you did your best, recognize that you're stuck at an advanced point, and just consult with the expert to learn something new (or reinforce a not yet fully integrated trick).
12:40 It happened again. Simon analyzes the 7s and 9s using the "empty rectangle" where i used finned X-wings. The results were the same. 14:10 Thanks. I didn't spot the bent triple. That finally cracked the puzzle for me.
17:31 for me. I found a very handy swordfish on 3's that really helped at the intermediate stage of the solving, and from there I applied uniqueness exactly once to aid my solve.
Very proud of myself: I think this may be the first time I managed to spot a Y-wing on my own! I'm a little sad I missed the empty rectangle: I was keeping an eye out for those early on but I guess I lost track of it. Managed to eliminate the 7 anyway with, effectively, a mini-slot machine, which is basically the same logic but without quite as much of an understanding. Still, pretty good!
Good puzzle, 1's and 8's moved things along very quickly, then a Skyscraper into a Y-Wing for me to crack it at the end. 12:55 for my solve time, which felt very solid overall. Got very lucky with some quick naked single spots as well that helped move the puzzle along. SPOILERS BELOW: An alternative to using the empty rectangle on 7's and 9's is to notice the skyscraper on 7's in columns 2 and 9. The possible positions of 7's in those columns are r4c2, r9c2, r4c9, and r8c9. This eliminated a 7 from r8c3 and r9c78 in the same manner as the empty rectangle does, and brings about the same Y-Wing that Simon spotted afterwards. For me, the skyscraper is a little easier to see than the empty rectangle, but in this specific scenario it accomplishes the same thing.
That sounds like my solve except I got completely stuck looking for that Y-Wing, it took me an embarrassing 40 minutes to finally find it despite hunting specifically for interactions between all the 3/5/7/9 pairs I had lying about! (SPOILER - this is what the puzzle looked like immediately before I finally spotted the Y-Wing, it was about the 3rd time I'd highlighted all the 3's... i.imgur.com/66LWHtc.png)
So this took me just over 25 mins and I got stuck 8 mins trying to spot the bent tripple that broke this puzzle wide open. Very fun puzzle real brain teaser!
Probably around an hour. I really struggled to find anything to make a difference for a while. A y-wing eliminating a 9 from row 9 column 2 was the critical factor, but I had used another y-wing and two finned x-wings previously with very little progress made to the puzzle as a whole. (I'm sure they helped later.) By far the hardest puzzle I've yet solved, thank you for the inspiration to keep trying. 11:15 You're so quick to spot those empty rectangles. I eliminated the same two numbers from the same cell using finned x-wings (for example, the 7s are on rows 6 and 8), but it took approximately a century to find them. 14:00 "Come on, come on! ... No, it can be a 9." Ahahahah, I know that feel. But I didn't even have the 59 filled in yet at r5c2 so I wound up going in circles for another long while before the y-wing/bent-triple showed itself and I could finish up. Not filling in the 59 was itself a consequence of never having entered the 8 right next to it -- it didn't look like a promising candidate for a double until after I corrected that oversight. Very interesting how these things go.
I found the same "bent triple"/Y-wing that Simon did, but I got to it without the empty rectangle. There was an upside-down skyscraper of 7s, in columns 2 and 9, that got rid of the 7s in r8c3 and r9c8, which revealed the Y-wing.
30m 59s Got stuck at the same point, but got there in the end, if different than Simon's way :) I found the symmetry of the 189's, 234's and 567's in columns 4 5 and 6 rather nice.
There's an interesting arrangement that pops up in the bottom right corner of the grid: r7c6, r7c8, r9c6, and r9c8 are 23, 34, 45, and 25 in a square. I don't know if there's a name for that arrangement, but it let me eliminate other 4s from r9 and 5s from c8.
Thanks Simon, I just solved this one and got stuck at the tricky part for some time. The empty rectangle is new to me, I eventually clawed my way out with a finned X-Wing but your method looks much better!
In a similar way as you did, the 7 and 9 in r9c8 can also be eliminated using a finned X-Wing on rows 6 and 8. Finned because of r8c9 in case of 7s, and r8c7 in case of 9s.
31 minutes. After staring for a while I started coloring every square that the sevens could go in and realized that one square had to be a seven no matter what
Oh God! That empty rectangle into bent tripple was too much for me after like 20 minutes looking into the grid and not able to do anything. Great work!
I got to the point before the empty rectangles, fully notated the puzzle, and did a bifurcation on the 7 9 pair, which solved it without too much difficulty. The 9 removes the 7 in the lower box after a short chain.
I don't think I'm a good solver but I managed to do it in 35:08 without /really/ getting stuck anywhere, I just started to look at each cell individually and deduced some things where only a single number could fit
Just under 12 minutes with a filling all candidates head start. A couple of Turbot Fish (I think you call them pincers) for some small gains, but it was a XY chain that broke it down. There were a lot of bi-value cells at that time so spotting the chain wasn't too difficult. Looks like your bent triple (Y-Wing) is the piece that got the same result as my XY-Chain. Definitely easier when working from an all candidates start. Good puzzle, thanks for sharing.
I guess I need to figure out the bent-triple thing better... I just took one of the pairs that get created toward the end and chained out a guess.. found it wrong and chose the other. Not super fun but I guess it did solve it.
9:05 // Don't think it was too hard, overall. Another example, I think, of how a Sudoku puzzle's difficulty isn't really related to the number of clues given at the start. Although I was, admittedly, more than slightly lucky to spot the Y-wing (bent triple) pretty quickly compared to how long they usually take to catch my eye.
I got to the sticking point and found a few empty rectangles (including the ones shown in the video) but they weren't enough to crack it, and I ended up bifurcating. So I guess it's time I properly learn the bent triple technique, which hasn't thus far been in my arsenal.
solved in 18:03 min for me. Now I will see Simon's solve. I noticed that this sudoku game has the minimum possible number of clues in classic sudoku (17). Edit: I used two 2-string kites (I learned it in Spanish as "cometa"), instead of empty rectangle: One in box6 for 7, and another in box4 for 9; reaching more or less the same conclusions.
Love this puzzle! No overly complicated techniques, but still some good ones in there. Imo the empty rectangles are not as elegant as using a 2 string kite to eliminate 7 from R8C3, which gives the XY wing a lot more nicely. Although, I also did some unnecessary stuff with the 3579 quadruple eliminating some candidates in R9C2 haha
I spent about ten to twenty minutes looking at that stuck-stage with a fully-notated grid then realized that a 5 in r9c3 would cause a contradiction in r7. different method, i don't think simon likes that kind of method though. still not sure i could ever notice a bent triple or anything like that~
Got me stuck for more than 10 minutes. but then @15:12 was that a y - wing??? Then i finally solved it in almost 30 minutes. I think I learned an empty rectangle technique thanks to them.
Once again my solver told me that this has no solution and when I put the 8 down in r7c7 it gave the puzzle fair rating. So how come my solver cannot see a naked single?
Hi Simon & thankyou for the videos helping me to progress beyond the Beginner stage of Sudoku. I particularly like this program/app that you send us to, to try out the puzzle. I'd like to use this program on my laptop on other Sudoku puzzles. Is it available to buy?
40 minutes. And I didn't spot the bent triple, I just tried to put a 4 in R9C8 and saw that after a (long) while it didn't work so it could only be a 5
It’s unlikely this is handcrafted. That’s a 17 clue sudoku with some very typical steps at the start. All authors I know that are good at classics are really proud of their creations with 20 or 21 clues. It‘s incredibly hard to get below that by hand and 17 clue puzzles are incredibly rare. It‘s also somewhat pointless since there are databases with 17 clue puzzles (around 50000 up to isomorphism) which are assumed to be almost complete.
Even with databases of 50000 puzzles, wouldn't it take a lot of praiseworthy human skill and effort to dig out the once that are 'beautiful' to humans?
I solved it in 15:29, then clicked Undo until my grid was blank and followed along. We lined up the same logic until the crux of the puzzle, where I took a shortcut by making a logical "mistake" that was luckily correct. I had "spotted" a 379 triple in c3 that wasn't really there, but I got the correct answer. ¯\_(ツ)_/¯
I'm at the 5 minute mark thinking this is far to easy where then comes the issue to make the video 18:16 because something is coming that I can't yet see and I always pause and solve 5 steps ahead of you myself and can't see how this is going to get any harder. Edit - GG I learned by minute 8 where the trouble rose and I had to stop and watch to figure it out! That actually helps for a puzzle I've been stuck on for ages at home I think!
![Classic Sudoku: Bonus Puzzle 4: [This is STUNNING]](http://i.ytimg.com/vi/O0uASyvv554/mqdefault.jpg)
Thank you so much Simon. I was too busy making pencil marks and trying to look around the grid for chains because I fully notated the whole puzzle. After you filled in the center box is where I hit the brick wall. Your bent triple to determine the location of the 7 and 9 was a very nice find. I couldn't find it because all of the pairs in the grid sent me on a dumb chains hunt. I feel somewhat dumb right now but I certainly am not anywhere near the solver that you are. Thank you so much for doing this for me.
You are most welcome. Glad we could help :)
I only managed to solve it using Mark’s favourite technique (make a guess and undo if you don’t get lucky!). That bent triple was a beauty!
I did the same, I was sure that the 59 and 79 held the key but I don't see how to resolve them.
That bent triple wasn't easy to see.
don't worry bud, i got stuck aswell at the empty rectangle step! i even looked around for empty rectangles & Y-wings, but i guess i haven't solved enough puzzles with such patterns to be able to recognize those patterns quickly enough. :)
Such a good payoff. I was stuck at that precise spot, deduced further from the 79 pair correlation and everything else fell into place. Awesome spot on the bent triple, too. It's just so rewarding to know you did your best, recognize that you're stuck at an advanced point, and just consult with the expert to learn something new (or reinforce a not yet fully integrated trick).
12:40 It happened again. Simon analyzes the 7s and 9s using the "empty rectangle" where i used finned X-wings. The results were the same.
14:10 Thanks. I didn't spot the bent triple. That finally cracked the puzzle for me.
17:31 for me. I found a very handy swordfish on 3's that really helped at the intermediate stage of the solving, and from there I applied uniqueness exactly once to aid my solve.
I got stuck on the same "nasty" step. Now I have to learn more about bend triples and empty rectangles.
only normal steps are needed. I don't use any of those and solved it no problem..
Very proud of myself: I think this may be the first time I managed to spot a Y-wing on my own! I'm a little sad I missed the empty rectangle: I was keeping an eye out for those early on but I guess I lost track of it. Managed to eliminate the 7 anyway with, effectively, a mini-slot machine, which is basically the same logic but without quite as much of an understanding. Still, pretty good!
Woah, hey, didn't expect to see you here! Good work on the music theory stuff!
Good puzzle, 1's and 8's moved things along very quickly, then a Skyscraper into a Y-Wing for me to crack it at the end. 12:55 for my solve time, which felt very solid overall. Got very lucky with some quick naked single spots as well that helped move the puzzle along. SPOILERS BELOW:
An alternative to using the empty rectangle on 7's and 9's is to notice the skyscraper on 7's in columns 2 and 9. The possible positions of 7's in those columns are r4c2, r9c2, r4c9, and r8c9. This eliminated a 7 from r8c3 and r9c78 in the same manner as the empty rectangle does, and brings about the same Y-Wing that Simon spotted afterwards. For me, the skyscraper is a little easier to see than the empty rectangle, but in this specific scenario it accomplishes the same thing.
That sounds like my solve except I got completely stuck looking for that Y-Wing, it took me an embarrassing 40 minutes to finally find it despite hunting specifically for interactions between all the 3/5/7/9 pairs I had lying about! (SPOILER - this is what the puzzle looked like immediately before I finally spotted the Y-Wing, it was about the 3rd time I'd highlighted all the 3's... i.imgur.com/66LWHtc.png)
So this took me just over 25 mins and I got stuck 8 mins trying to spot the bent tripple that broke this puzzle wide open. Very fun puzzle real brain teaser!
its not called bent triple. its a Y-WING
www.sudokuwiki.org/Y_Wing_Strategy
Where he said, "Is this where you got stuck, Matthew?" ... that's exactly where I got stuck :(
Simon is clearvoyant.
1:06:53 on my end. My methods are simple and I don't have a quick eye.
10:45 it took me 20 minutes to get there, but that's about where I got stuck too.
Probably around an hour. I really struggled to find anything to make a difference for a while. A y-wing eliminating a 9 from row 9 column 2 was the critical factor, but I had used another y-wing and two finned x-wings previously with very little progress made to the puzzle as a whole. (I'm sure they helped later.)
By far the hardest puzzle I've yet solved, thank you for the inspiration to keep trying.
11:15 You're so quick to spot those empty rectangles. I eliminated the same two numbers from the same cell using finned x-wings (for example, the 7s are on rows 6 and 8), but it took approximately a century to find them.
14:00 "Come on, come on! ... No, it can be a 9." Ahahahah, I know that feel. But I didn't even have the 59 filled in yet at r5c2 so I wound up going in circles for another long while before the y-wing/bent-triple showed itself and I could finish up. Not filling in the 59 was itself a consequence of never having entered the 8 right next to it -- it didn't look like a promising candidate for a double until after I corrected that oversight. Very interesting how these things go.
I got stuck in the same position twice, the bent triple really worked magic here. The third time I could solve it. Very instructive indeed!
Took me 25 minutes, enjoyed it a lot. Half a year ago I would never have been able to solve this, so thank you Simon & Mark!
i got stuck at exact position @10:55 ...I couldn't see empty rectangle - Simon is good at spotting them.
although @6:30 I spotted "6" in r4c4
I found the same "bent triple"/Y-wing that Simon did, but I got to it without the empty rectangle. There was an upside-down skyscraper of 7s, in columns 2 and 9, that got rid of the 7s in r8c3 and r9c8, which revealed the Y-wing.
I never saw the bent triple that others are talking about but did 2 empty rectangles and a mini logic chain and it solved the puzzle
30m 59s Got stuck at the same point, but got there in the end, if different than Simon's way :)
I found the symmetry of the 189's, 234's and 567's in columns 4 5 and 6 rather nice.
Thanks for telling me what a bent tripple was. I would never have found the solution without it.
There's an interesting arrangement that pops up in the bottom right corner of the grid: r7c6, r7c8, r9c6, and r9c8 are 23, 34, 45, and 25 in a square. I don't know if there's a name for that arrangement, but it let me eliminate other 4s from r9 and 5s from c8.
Thanks Simon, I just solved this one and got stuck at the tricky part for some time. The empty rectangle is new to me, I eventually clawed my way out with a finned X-Wing but your method looks much better!
In a similar way as you did, the 7 and 9 in r9c8 can also be eliminated using a finned X-Wing on rows 6 and 8.
Finned because of r8c9 in case of 7s, and r8c7 in case of 9s.
This was how I solved it. I'm usually hopeless at spotting them but it jumped out this time.
Indeed, that's what I did.
31 minutes.
After staring for a while I started coloring every square that the sevens could go in and realized that one square had to be a seven no matter what
This is pretty sick dude! Keep up the great work!
Oh damn i've been stuck for 20 min, i'm amazed at all these new tricks every time.
Got stuck at the tricky part. I think I am finally starting to wrap my head around empty rectangles. Thanks for the videos they are really great!
Oh God! That empty rectangle into bent tripple was too much for me after like 20 minutes looking into the grid and not able to do anything. Great work!
16:42 for me, feel pretty good, specially since I did it on my phone
Brilliant deduction. Thanks again for the tips
I got to the point before the empty rectangles, fully notated the puzzle, and did a bifurcation on the 7 9 pair, which solved it without too much difficulty. The 9 removes the 7 in the lower box after a short chain.
I don't think I'm a good solver but I managed to do it in 35:08 without /really/ getting stuck anywhere, I just started to look at each cell individually and deduced some things where only a single number could fit
Just under 12 minutes with a filling all candidates head start. A couple of Turbot Fish (I think you call them pincers) for some small gains, but it was a XY chain that broke it down. There were a lot of bi-value cells at that time so spotting the chain wasn't too difficult. Looks like your bent triple (Y-Wing) is the piece that got the same result as my XY-Chain. Definitely easier when working from an all candidates start. Good puzzle, thanks for sharing.
My proudest solve thus far at 16 minutes, less technique based and more thinking ahead and following paths got me through it really quick :)
I guess I need to figure out the bent-triple thing better... I just took one of the pairs that get created toward the end and chained out a guess.. found it wrong and chose the other. Not super fun but I guess it did solve it.
9:05 // Don't think it was too hard, overall. Another example, I think, of how a Sudoku puzzle's difficulty isn't really related to the number of clues given at the start. Although I was, admittedly, more than slightly lucky to spot the Y-wing (bent triple) pretty quickly compared to how long they usually take to catch my eye.
Wow... I totally missed both of those tricky steps. I really envy your skills on this...
I got to the sticking point and found a few empty rectangles (including the ones shown in the video) but they weren't enough to crack it, and I ended up bifurcating. So I guess it's time I properly learn the bent triple technique, which hasn't thus far been in my arsenal.
solved in 18:03 min for me. Now I will see Simon's solve. I noticed that this sudoku game has the minimum possible number of clues in classic sudoku (17).
Edit: I used two 2-string kites (I learned it in Spanish as "cometa"), instead of empty rectangle: One in box6 for 7, and another in box4 for 9; reaching more or less the same conclusions.
Love this puzzle! No overly complicated techniques, but still some good ones in there. Imo the empty rectangles are not as elegant as using a 2 string kite to eliminate 7 from R8C3, which gives the XY wing a lot more nicely. Although, I also did some unnecessary stuff with the 3579 quadruple eliminating some candidates in R9C2 haha
Thanks for the tip about the bent triple! In my solve, I was just StaRiNg at it hopelessly, my logic totally failing me haha
Would love to see you try a Samurai Sudoku, very challenging but interesting to complete
I spent about ten to twenty minutes looking at that stuck-stage with a fully-notated grid then realized that a 5 in r9c3 would cause a contradiction in r7. different method, i don't think simon likes that kind of method though. still not sure i could ever notice a bent triple or anything like that~
I got it in just under half an hour, which is fantastic for me. Usually I solve within 30-90 minutes. I expected it to be more difficult.
More classic sudoku pleaseeeeee
I was stuck, but now I can see how a bent triple works. I plugged this into a mobile app to work on and it couldn't even validate it as unique.
Got me stuck for more than 10 minutes. but then @15:12 was that a y - wing??? Then i finally solved it in almost 30 minutes. I think I learned an empty rectangle technique thanks to them.
Once again my solver told me that this has no solution and when I put the 8 down in r7c7 it gave the puzzle fair rating. So how come my solver cannot see a naked single?
Hi Simon & thankyou for the videos helping me to progress beyond the Beginner stage of Sudoku. I particularly like this program/app that you send us to, to try out the puzzle. I'd like to use this program on my laptop on other Sudoku puzzles. Is it available to buy?
Bifucated on a 35/23/25 daisy chain in row 7 and solved in twenty minutes. Nice!
40 minutes. And I didn't spot the bent triple, I just tried to put a 4 in R9C8 and saw that after a (long) while it didn't work so it could only be a 5
you Don't need any wings, empty rectangles or bent triples. Normal row, column and box logic is all that is needed..
29:20 not too hard worked slowly through it
It’s unlikely this is handcrafted. That’s a 17 clue sudoku with some very typical steps at the start. All authors I know that are good at classics are really proud of their creations with 20 or 21 clues. It‘s incredibly hard to get below that by hand and 17 clue puzzles are incredibly rare. It‘s also somewhat pointless since there are databases with 17 clue puzzles (around 50000 up to isomorphism) which are assumed to be almost complete.
Even with databases of 50000 puzzles, wouldn't it take a lot of praiseworthy human skill and effort to dig out the once that are 'beautiful' to humans?
32:07!
i'm weak on bent triples ...
I understand them well but can't ever spot one
I... I got this puzzle in 10:08 with no problems at all. I must have gotten lucky as there was no cleverness needed to solve it...
me too. you Don't need any wings, empty rectangles or bent triples. Normal row, column and box logic is all that is needed..
I have been doing a puzzle called ‘Binary’ for a few days now, finding them a lot of fun! Would be nice to see one on the channel?
01101110 01100101 01110111 00100000 01110000 01110101 01111010 01111010 01101100 01100101 01110011 00100000 01100001 01110010 01100101 00100000 01100110 01110101 01101110
need empty rectangle tricks and xy wing trick.. good sudoku!!
30:39 but I was watching along while solving *yikes*
Can we start a fundraiser to get him a better microphone?
That puzzle was a 17-givens.
I got stuck at 11 minutes the same place you did.
I solved it in 15:29, then clicked Undo until my grid was blank and followed along. We lined up the same logic until the crux of the puzzle, where I took a shortcut by making a logical "mistake" that was luckily correct. I had "spotted" a 379 triple in c3 that wasn't really there, but I got the correct answer. ¯\_(ツ)_/¯
yaay, I managed to solve one without any help from you or your video :D 21:50, #proud
You keep mentioning a Facebook group you're apart of mark. What's the group?
I'm at the 5 minute mark thinking this is far to easy where then comes the issue to make the video 18:16 because something is coming that I can't yet see and I always pause and solve 5 steps ahead of you myself and can't see how this is going to get any harder.
Edit - GG I learned by minute 8 where the trouble rose and I had to stop and watch to figure it out! That actually helps for a puzzle I've been stuck on for ages at home I think!
Nice video
wizardry
Spoiler alert - I found the triple, It also gives you the 3 in the upper left corner of the right-hand middle box which completed the puzzle for me.
Good
A bit over 28 for me. :)
i tried it and it took me 40 mins. then i look at the video... 18 mins. but im not a math magician, sooo.
9 minutes 27 seconds.
you don't need any tricks for this one. normal easy sudoku methods apply