Techniques for Starting Hard Sudokus
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- เผยแพร่เมื่อ 1 ส.ค. 2024
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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
Aside from their prodigious solving abilities, I do envy Mark and Simon's ability to scan a row of 7 or 8 numbers and immediately know which ones are missing. I have to count up from 1 each time.
I have to do exactly the same. Finding naked singles, let alone naked pairs, can be somewhat tedious.
I'm getting better at it, but it certainly takes some doing.
Me too. I guess if you do enough of them you get better at it, although it does seem at times that it's just a special talent that I'll never have.
The way that I do it quicker is not by reading it but looking for the shapes, if it looks like the shape 6 is missing then that is it. Reading will slow you down.
@@Whatevsbabes Yes I think that's the right approach but not sure I would trust myself not to mess up.
"That's a naked single..." Made me check if my webcam was on again...
I'm a big fan of how clearly you explain what your steps are. It's a massive help at times.
Grief that's hard! I feel like I learned something but I have no idea if I'll remember to apply it next time lol
Thank you, Thank You Thank You!!!!! I did it, it took me an hour, but I did it. Watching you and Simon has really paid off. I spoted a pair and it slowly led me to solving the entire puzzle!
Gene
I do my sudoku from a book by hand. I really need to switch to digital because it makes the process soooo much smoother. I recently found this channel and i love how complicated these get. Cant wait to get my hands on some of these myself, love a good challenge!
I'll have to start looking for pairs of digits in two columns or rows more often. That actually helped in other parts of the puzzle. There were other ways of doing it, but it's nice to be able to spot things right away that would otherwise take a lot of pencil marking.
30:24 for me. Interestingly enough, I went a completely different route than Mark did.
I found a hidden 23 pair in column 7 which gave me the 1 in that column and followed normal sudoku logic to get to where he was at 10 minutes. I then found a naked single 9 in column 4 which he talks about after explaining his more advanced and complex logic without using his advanced complex logic, and the puzzle logically followed from there without using any complex techniques.
It's so fascinating that there are so many varied approaches that can arrive at the same solution.
I found the same pair! I started looking at the 745 in lower left box and scanned col3, close but not enough, then upper right at 321 and col 7. Jackpot. Took like 10 seconds, amazed my self :-)
I went through this route too!
Awesome find.
@@DigitalizedArtist Looking for pairs in this way was totally new to me until I hit this puzzle. It takes some logical thinking for it all to sink in.
45 minutes for me. Only 3 times as much as Mark, which I would call a huge success.
Watching you guys made me do so much progress those last few days and has renewed my interest in sudokus and puzzles. Thank you very much!
Found this channel because ive always loved sudokus and i wanted to be better on them (quarantine times make you want to improve on something or learn new things) and now i cant stop watching your videos and learning a lot from them... They are a good way to expend my time when i am not doing some university stuff
Keep the good content!!!!!
My first time actually playing one of these, 2:02:26 with my only previous sudoku experience coming from the built in Windows 10 version of the game. I just had to watch a couple of clips to get past a mental blockage :)
2 hours for a sudoku???
Thank you very much for this solve. I thoroughly enjoyed your commentary on this Sudoku and picked up a few tips along the way to aid me in my solving.
Thank you so much for your videos, you both have a gift with solving puzzles. I have enjoyed doing standered Sudoku for over 20 years, and never seen most of the ones you guys are showing. I don't go for speed, I just enjoy a good puzzle..
Mark made a blooper in 4:41. It is now confirmed that he is a human. Unbelievable
I think it's his touchpad. He seems to have a lot of problems with it.
that was staged....done on purpose to throw you off. looks like it worked
I like the walkthroughs of hard regular Sudoku. I followed along and tried to make sure I understood everything you did.
At 4:00 the way you found the 39 pairs on the row was just amazing. There is no method for spotting such things in a sudoku. You have to have it in you.
I filled in all the combinations on all empty cells, and specifically went looking for triples. I accept that I can't spot them like Mark and Simon. Sigh. I did however use that New York Times technique and get several numbers in this puzzle. So I've learned that much!
ahhhh Cracking the Cryptic Classic Sudoku puzzle 11
so glad youtube recommended this fine channel, with these two smart english men. good stuff! that puzzle was hard
i just got into puzzles recently. this guy is absolutely bloody brilliant. would that i could go through each step that took me 10 minutes per; each of which he did in 20 seconds
An hour to solve it, but the first one I solved without watching the video first! This channel has definitely helped me to improve a lot in solving these :D
This puzzle is Level 11 on the Classic Sudoku app on Steam!
That sounds about right. This is the first puzzle that I've had to fight every step of the way just to get numbers in.
I remembered it because me and some friends coincidentally were working on the puzzle yesterday! It took 4 of us 23 minutes just to place the first note...
I THOUGHT it felt very, very familiar! I've solved every single one of the puzzles in the Classic Sudoku app, and the start with the 23-pair in column 7, the 39-pair in row 8, the 123-triple in box 2, the 12--pair in row 1, the many 57-pairs in the grid, the 578-triple in column 6, and more felt so, so familiar to me.
That’s hilarious that he didn’t realize that. 🤣 But I guess you can’t always remember such things, after a while, they all run together.
Lmao I got stuck on this puzzle too
Neat puzzle. The start may be puzzling for a while, but once you realise the positions of the 3s and 9s create that 39 pair in row 8, the puzzle gets relatively easy. I needed just under 20 minutes at my slow pace to do it without entering any pencil marks. There was a very nice flow to the puzzle. Once I found the 57 pair in row 5, central block, that was it.
Step 1: Click to the end.
Step 2: Fill in the numbers.
Step 3: Post unreal time in comments and feel great.
By the way, I finished this in 1:23.
What took you?
1:14:27 These are just too hard for me. I want to relax a bit with a puzzle but I get stuck too often and waste too much time on this. Love the videos. I would never attempt these puzzles without them. Some of the puzzles on this channel are really, really great!
Love this channel!! So pleasing!
33:41 for me. The 1 and 6 bit really in the middle really helped clear it up once I figured it out.
38:16 for me, feel really good about that :) Enjoying the channel loads, keep up the good work!!
*Me playing soduku still counting what number is missing in a row or column.*
Them: "there's 8,7,6 to fill in there"
Lol, tricked into solving an app puzzle. Not mad at all about that. I needed the help.
Thanks to you I learned about hidden tripplets, and that's how in this puzzle, I placed 1 as my first digit
I picked a new trick.Very helpful.Digitally solving has it's perks.I'm learning to use pencil marks now.I always used a pen before
Big fan of the clear explanation :) keep it up
I couldn't solve it, but I learned a new technique. Thank you!
Rather neat that very similar logic to your 79 pair can get you started with a 23 pair in column 7 as I found as my opening.
"I wasn't unhappy with that" = almost happy!
51:53 and believe it or not I'm pleased with that. (relative beginner). Thanks for what you do.
Thanks. Nice puzzle.
Wow nicely done thank you
8:23 for me...hardest thing was a type 1 unique rectangle. Nice puzzle!
It's so easy to solve these when someone shows you how!
52:50 This one beat me up … I ended up bifurcating twice (and erred on one of those the first time through).
Between this one and the other one from today (which I couldn't solve at all), today was just a really bad day for me.
EDIT: After watching the video … it was the 3-9 trick that I had missed; that led me to finishing it without bifurcation.
43:16 was my first time beating this. Tough one!
Then I got the tip about naked doubles from the CtC app and had to see if this would speed up the solve, which it really really did.
Instantly spotted the new york times hidden triple in column seven. Puzzle was decently easy after that.
done after 55 minutes. but i must say that i had 2 situations where i tried a number without being sure. so i watched your way and after 3 minutes my first try was destroyed by your logic :D
This is the first time for me to use this technique to find 23 & 39 pair, although I watch CTC for 2 months. I feel that I learn a lot skill. however, it also take me 45 mins.
Some of the special puzzles are very hard, but some of them actually have decent structure and make it easier for me than a classic puzzle.
I found two triples right at the start, which allowed me to make very quick progress at the beginning, but then it took me quite a while to find one final triple in the top middle box, and it ended up taking almost half an hour. You did it way differently though.
Pretty simple once you know to look for naked pairs. 17:12 for me... I'm definitely getting faster thanks to this channel
I think there needs to be another video on empty rectangle technique, explained for dummies such as me
And Me!
9:03 for me. I’m pleased with that.
After the 39 pair gave a bunch of numbers I found the naked single 9 much earlier and followed a different path, but still ended with the 57 pairs all over the place, including helping in the top row.
A very beautiful puzzle indeed
I solved this puzzle on the app yesterday. Took me slightly over an hour and placed 0 digits the first 25 mins.
I managed to get started. The first digit I got was the 4 in the top right box!
Made a silly mistake 1 hr 20 in. Gutted!
I just had a random idea for a sudoku constraint. Magic 5's.
Basically wherever a 5 appears the connected squares can have a difference of 1, 2, 3 and 4.
Meaning that if it connects to four numbers then they can be 4 or 6, 3 or 7, 2 or 8, and 1 or 9, with only one number appearing from each set. Meaning that if you find 6 attached to 6 then 4 cannot appear connected to that particular 5 as well.
Seems like an interesting concept to me at least.
21.06
ty for the puzzle
That 3,9 pair was the game changer.
OMG that was a struggle!
I was doing good until 9:42.
A few more of 'only 2 possibilities in a box' pencil in but had no idea how to go forward.
Eventually came to the video and while I get the logic a part of me still feels like that's guessing for my current level.
It feels very much like searching for X wings and it's certainly not something I can 'see' even while searching them.
Still waiting for the day it clicks in my head until then... practice practice practice.
Thank you, have been enjoying watching your videos.
7:37 for me, tricky start, slight bump in the middle.
19:04! That's really good for me I'm proud
Well done! :)
Hi, i'm pretty new in the sudoku things and all of that, and i'm not a native speaker of english. So i need help with te trick in the min 3:48 with the 3 and 9, i felt really lost about that, i can't get why block the row 8, Any buddy can explain me why was that?
This one stumped me hahaha
Something you could also have done at the start of this puzzle, was the NYT trick with the numbers from box 3 and their affect on column 7
That has become my first step in solving puzzles. I always give a quick glance for an empty row/column within a cell before I start placing candidates. It definitely helped here.
same NYT trick works with box 8 and its effect on row 8. right off the bat
I got pretty far at first, but was then stuck for 90 minutes, and finally gave up.
I would never have noticed that central 1,6 combo on my own.
Nice
Nice puzzle, to me it was very surprising that you didn't spot the 'new York times' trick in column 7, but still, good work
started with 2 & 3 in row6 & 7 and box3 to place the 1 in row7. got the 9 in row3 somehow to make 5, 7, 8 a triple in box3, then i spent 10 minutes looking at a naked single 1 in column 6 xd
link to the puzzle doesn't work :(
This puzzle is in the app and I’ve been stumped by it for two days!
Yeah, this one's kicked my ass, too. Accumulatively, I finished it in about two and a half hours and my forehead is throbbing from the strain. When I watched the video and saw him easily put that triple into column one, I had to pause the video in order to comprehend what he did while stewing in my juices for not having seen it for myself.
r0bw00d mercifully I finally knocked this out tonight. I’d say I was approaching 2.5 hours cumulatively as well.
WOW
I was stuck
How did you see those 3 and 9s (giving us the 7 in block 9) ?!
EXCELLENT
Knew I had to tune back in for a hint lol 😅☕
I could follow you until 11:13, then I lost your reasoning. The pair from mid square mid-top (1567) to mid-bottom (146) to bottom square mid-bottom (16). Why can't the top square middle column not be 1's? The bottom one is blocked by a 1 on the 3rd row. What if that middle column mid square has top 7, mid 5, bottom 4 & at the bottom square mid 6, then the top of that column can have 1's.
Jade Smith
: Yes. That's the bit I'm still trying to understand, I've watched it over and over and i still don't get it.
This is where I am stuck too. I would understand if the 1 or 6 were in the same column, but I don't see the logic of why it cancels the three boxs out up the middle. It's a 1 OR 6 not 1 AND 6.
Edit: Since I didn't understand the logic, I found another route by finding pairs in the top row and right column resolving the 57 pair then the 9 had only one place on the top row.
"What if that middle column mid square has top 7, mid 5, bottom 4 & at the bottom square mid 6" if you do this, middle square can't fit 1 and 6, the puzzle breaks
@@TommyTomLP : Thanks, I'll check that out.
Box 5, bottom left. Pick either 1 or 6, either way then there must be either 1 or 6 in the middle column of box 5 somewhere. Therefore the 1,6 pair in box 8 must be the opposite. This proves that there must be a 1 in either box 5 or box 8 at column 5. Therefore there can't be a 1 in box 2 at column 5.
15:04, I need to keep working on spotting hidden doubles.
There was a 579 triple in the top row at one point, which left 12 pair, but that is the only thing I spotted Mark didn't.
Been a while since I did a hard classic. I needed help seeing the 3-9 break in, then it was just a hard slog of looking.
I definitely learned something. I am not as good at sudoku as I was.
It took me 76 minutes. What a brutal puzzle lol
Had to watch the trick at 11:00 three times before getting it, and I've been doing sudoku for 15 years. Wow.
can you explain this? For me there is no 1/6 Pair in C5R4 or in C5R6. He self hat a possible 4 there at this time. I dont get the trick there.
@@bytegecko2813 Look at R9C5. It's either a 1 or a 6.
If it's a 1, then 1 is eliminated as a candidate from the center column of Box 2.
If it's a 6, then R6C4 is also a 6. Since 1 cannot be in row 5, it must be either in R4C5 or R6C5, which also eliminates 1 as a candidate for R1C5 and R2C5.
R6C4 = R9C5. The matching "pair" to both is either in R4C5 or R6C5. It doesn't matter which to logically eliminate the rest of C5 as potential locations for either 1 or 6.
Sir, Your videos on Sudoku are excellent. But your play list must cater for Sudoku enthusiasts from basic level of Learner to finally Expert. Kindly rearrange explaining basics of sudoku in first couple of videos. Then go to solving puzzles of Easy level. Scale it up later to Medium level, then on to Hard level and finally to Very difficult / Expert / Diabolical puzzles. This way you will be attracting more subscribers. Thank you for your efforts to popularize Sudoku,
Must've misplaced a number at some point, cause it completely messed up for me. Restarted and got it in about 50 minutes after that.
This puzzle had a world record for slot machines, but none of them worked! Just had to go old school on it.
I would take a second to check the base and battery of your laptop. I've seen many many instances of swollen batteries pressing up against the bottom of the trackpad and causing all sorts of issues, including false inputs.
Can someone please tell me what the rule is where you just immediately jumped to a 93 matching pair conclusión at the start of the video? Thx!
He spotted a 3 9 in both the third column and the ninth column, and also a 3 9 in block 8.
So looking at the bottom three rows, he looked orthoganally and where are 3 and 9 going to exist in those other two blocks? Row 8 jumps out because it does not have a 3 or 9 in it. So I think he asked where can 3 and 9 live in Row8?
On R8, the two numbers 39 cannot exist in:
Column two, already taken.
Column three, 39 in cells above.
Columns 4,5,6, a 39 in the box 8.
Column 7, already taken.
Column 9, 39 in cells above.
Thus the only empty cells in row 8 for 3 and 9 are in columns 1 and 8.
A 39 pair.
How they see these things at a glance just amazes me!
Hope this helps. It's not how I found it on my own, I am so much slower. I filled in all the possible numbers in every cell, and then I looked for triples and found 739 on row 8. And found several through the New York Times trick they teach. Sigh. But at least I found it and I am better than before I started watching the channel.
Oh my dog, I couldn't do this one. Puzzle 11 in their classic sudoku app. And he does it in 15 mins
What the difference in your technique between placing pencil marks in centre or corner?
They go over it often in some older videos. Corner notation is saying "in this 3x3 box, this number can appear in only these cells" They often only do this for when a single box has only 2 possibilities for a number. This is called "Schneider notation"
If they notate the center of a cell, it's saying "this cell can only contain these digits". Often used when notating pairs/triples in rows or columns.
My time: 19:00 even. Exactly what kind of "hard" sudoku was this, I didn't even find any X-Wings ... but I did have to consult your solve for a hint when I discovered a mistake (I'd placed a 5 in r6c4 after incorrectly tagging a pair elsewhere in the center box. Whoops).
BEST
there is also a 123 hidden triple in column 7. 1, 2, and 3 are ruled out of rows 1, 2, 3, 4, 6, and 8. that means the 123 must be in rows 5, 7, and 9 which can be solved for. I didn't see that 39 trick for row 8, that was really nice.
NY Times trick. Similar to what he did in row 8.
@@1fosters indeed. I've seen Simon and Mark use it before, but it's my first time personally spotting it, so I'm inordinately proud of myself lol.
I was following along until 13:28. What makes C5R2 a 5-7 pair?
That row had only 3 empty squares - 5-7-8. That square can't be 8, thus it's 5-7.
35:35. I didn't spot the 39 pair. I found r8c3 had to be 168. Which ever one it is, it finishes the r7c4,r9c5,r7c6 triple with 4 and 5. That excluded the remain two digits of 1,6, and 8 from r8c1. That left 39. The second 39 was easy to spot, and, off to the races. In box 3, after the 9 is placed in box 9, r1c7 is 79, and r1c8 is 57. The 57 forms a pair with r1c3's 57 putting a 9 in r1c7.
That was just WOW!!!! The ability to scan the whole board and find patterns to eliminate possibilities and hone down on pairs!! Makes it look easy, but it aint.
35:12, this one was harder than i thought it would be
16m35s for me. This wasn't too hard as I found the hidden 2,3 pair in C7 pretty fast. Curiously I completely failed to spot the hidden 3,9 that Mark found.
I did it by putting 4 in r2c9 as my first digit.
32:19 for me ended up having to color the 57 pairs at the end to figure our which was 5 and which was seven
@10:00, by uniqueness, r8c5 must be a 28 pair
Is it valid to argue that (for the three 1/6 cells in boxes 7 and 8) the one above the 1/6 cell in box eight must be an 8, because it can only be 1/6/8 and not putting in an 8 would result in a 'deadly pattern'?
In this particular case, I question the validity of that strategy at all. Mark said the source had been ungiven, and it sounded like it had been untested, so there’s no indication that it actually had only one solution. Competition puzzles are pretested, so it’s guaranteed, and computer algorithms don’t usually output multi-solution puzzles, either. But a random unsourced puzzle could be just straight up broken.
That said, Mark and many commenters have solved it using no assumptions, so technically yes you could do that given that information.
20 minutes staring at it without any clue, then watched until he got the 39 pair from where I could solve the rest in 40 minutes.
pretty much the same as me mate! cool starting trick
Same for me
At 10:33 you may place the 5 in r4c9. If that cell was a 2, the solution wouldn't be unique (r4c7, r2c8, r2c9, r9c7, r9c8).
Also at 12:08, uniqueness can be used to put the 8 into r8c5.
I dont quite get the logic at 11:01 - how can we be so sure there is a second 16 pair in column 5 / box 5?
Because Column 4,6,9 , will always have a 1 put there regardless of what's put in R6 C4