Advanced Tutorial by UK Sudoku Champion

We are delighted to host this video from Tom Collyer, the reigning UK Sudoku champion, in which he discusses some techniques that can help all our solving.
The first puzzle used can be played here: app.crackingth...
And the second puzzle is here: app.crackingth...

[@sandyhafenbrack141]

I spent the whole puzzle screaming "FOUR! THE FOUR!!" at the screen.

[@ridefast0]

What amazes me is the way that these experts seem to spot an X-wing, Swordfish etc even before the candidates are pencilled in! Highly impressive.

[@emilywilliams3237]

Touring older videos, and this was quite interesting as a video, and quite interesting to hear another voice and method solving on this channel. But what struck me very strongly was the value that CTC has exhibited of generosity - sharing their platform with a guest not only in this video but in several others, and also their (rightly) insisting that the beauty and elegance is in the mind and creativity and skill of the constructors, not so much because of the solver. Thanks for this video and for all of the excellent content on CTC over the years, Simon and Mark. You are well deserving of over half-a-million subscribers and all of the plaudits you have received.

[@milkom2021]

I usually have a hard time spotting hidden triples so in the first puzzle I cracked it open with a Unique Rectangle at AB39 The second I've done with the aid of the 79 pair in box 9

[@ldm125]

Definitely a lightyear past where I am as a solver but really amazing to watch.

[@KusaneHexaku]

@@firstaidsack yeah, and they are using it correctly, so?

[@rabidsamfan]

Thank you. I need more marks to spot the patterns you do, but it's fascinating to watch you in action.

[@ozertamer210]

A lot of questions raised like how did you do that number to that box etc. even if they can watch it again and again. Here is an explanation of full set of solution by NOTATION of Sudoku. I just followed Tom's solution by written text. I did not offer any trick to solve it.

[@milkom2021]

I find the noises his mouse and keyboard produce strangely satisfying 😊

[@achucanda760]

I am happy to say that I have used the Unique Rectangles Type 4 (Also 3 works) to solve the first puzzle SUPER !

[@ulisesx1605]

Are you kidding me…what was that godlike calculation with the 2’s in the beginning wow

[@javabeanz8549]

I sure didn't see that X-Wing on 4's, but once you showed the first one, I used it to eliminate candidates and found a second X-Wing on 4's, and that cracked the puzzle for me. Once the 4/7 locked pairs in box one were solved, it just flowed.

[@williamb2845]

Any chance you guys can turn up your mic on these tutorials? Hard to hear you.

[@desertodavid]

I clicked this off after 38 seconds horrible audio. To make it worse he's smacking his lips. You don't do that when you're speaking in public especially on a microphone.

[@27scole]

It's alright

[@o.o99]

Could you explain how you put 2 in box 5 with only three 2s in box 3,4and 7 at the beginning?

[@K9D1C3]

im lost with that too, and he just started

[@w00ki12]

Because if you look in box 6, the only place the 2 can be is in row F because the 2 above (in box 3) restricts it. Working from that, the 2 can only be at the top of box 5, and from that only in column E of the box

[@wossaaaat]

I used uniqueness at that sticking point. You already have the 46 pair in box 1, and it's fairly apparent that you have a 6 pair in C9 in the corresponding rows, so the 4 had to be in C8 for box 3... that resolves the 4 in box 9, and I could sloooooowly work out the rest of it with simple snyder. No amount of practice will get me to spot patterns like the one recommended, especially at that speed... my brain just doesn't work -that way.-

[@MyReligionIs2DoGood]

On the second sudoku, did anyone else spot the other X-Wing with 4s in R1C68 and R5C68 which immediately solves the 4/7 pairs in C1 and cracks the puzzle open? Thanks to CtC, and specifically Simon, who gave me all these great techniques, and back with them the excitement for this game.

[@ridefast0]

Might be a silly question but please say, why did you leave the centre square blank for so long? Could it never help with anything else?

[@ridefast0]

Can answer that myself now - it was indeed a silly question. Sorry.

[@lookingfortruth1930]

ridefast0 don't worry at least u know now

[@achucanda760]

I think as he said at the end, he forgot to fill it but it couldn't help HAHAHAHAH

[@ozertamer210]

It shows that his brain is working on different way. That 4 did not affect anything. He filled it last. He focused on other structures on the puzzle.

[@stan1036]

Tom: "Let's do the easy ones first" Me: has to pause and scroll back for EVERY bl**dy number he fills in :-)

[@soumynonareverse7807]

Sorry, but with that speed I was totally lost in the first half minute. I think for next time, could you explain why you placed each digit at a certain place, no matter how easy it might be for you?

[@lexiscontos2521]

For real, it’s supposed to be a tutorial 😂

[@wrathfeeling]

5:37 around here. I see the bottom right, the 2 and 8. To the left of it is the green box with the 1 and 5 pencil marked. Going up from that box you see the 5s pencil marked. That makes 3 places a 5 could go. Still the box above the green box with the 1 and 5 pencil marked can still contain a possible 5. Not sure how the green box could be filled with a 5. Since it doesnt looked certain yet.

[@fabiano.w.3019]

the box 3 can only contain the 5 in the left column, so you can eliminate it from the bottom cell (the green one) and put the 1 there

[@goldenera7090]

real Master Tom. I think he is from different planet - Planet Sudoku :)

[@27scole]

great video

[@w00ki12]

Can anyone explain how we worked out placing the 3 (in box 9) at 6:22 and then the 4 and 1 in the same column after?

[@martinbrousseau2132]

By exclusion. That cell could see every other number but 3.

[@GaryNewtonBrowne]

3rd number to go in is a 2 in the central box. Yet there are 3 cells a 2 can go. Two in the bottom row as well as the one in the top row. How did you eliminate the bottom row?

[@lsmart]

In the right-middle grid, the 2's can only go in r6 because of the 2 in r1c7, and in the left grid there is a 2 in r5, so in central grid it must go in r4, and it cannot go in r4c4.

[@joshc3400]

Is there multiple ways of solving or just one?

[@fritzeckstein95]

13:50 . i dont get how he puts the six up into block 3 using the xwing (im also new to the xwing, but i see nothing having to do with the six) # feel dumb

[@hariman7727]

It's an interaction between the x-wing on 4s and the 5/8 pair. The 5/8 pair means there's only room for 4 and 6 left in the box. The X-wing means the 4 can only go in the corner square of the x wing, and not in the top right corner, so the 6 must be in the corner. The x-wing is when two rows (or two columns) have a single number restricted to 4 individual spots that form a square. Because the number in question (4s in this case) can only be in those four spots, the number MUST be on the corners of that square, meaning that both the row and the columns extending through those four spots cannot contain that specific number. It's a technique that shows that places that you can't put a specific number, which often points to places you can put other numbers by elimination of what can't go there.

[@xCupressocyparis]

@@hariman7727 I could never understand the x-wing until I read your clear explanation. Now I feel I have a chance of spotting one if it comes up. Thanks very much! 🙂

[@hariman7727]

@@xCupressocyparis you're welcome. :)

[@davidwells1508]

Not sure why a 4 could not go in the top right hand corner.

[@lsmart]

That is the whole point of the x-wing. Once you find an x-wing in rows a and b, wherein the particular number is limited to columns c and d, that number can be eliminated from every other cell in columns c and d. Here, he has a 4 x-wing in rows 2 and 6 and columns 5 and 9 (at 13:37). Thus, there cannot be a 4 in r1c9.

[@yashwani612]

how is he solving that fast

[@milkom2021]

He made that one lol

[@espitianava]

THE FOUR 👁👄👁

[@salvaresi]

How did he find that 8,9 pair on C4R3 and C5R3? Isn't that 9 also possible on C3R3 and the 8 possible on C7R3?

[@Raven-Creations]

Yes, but once the 4 was eliminated, those two cells (C4 & C5) could only accept 8 or 9, so the 8 and 9 must be in those cells and can therefore be ruled out of the other cells in R3.

[@puzzlechannel4530]

i like this kind of puzzle

[@jerichopaulespiel9873]

how do you get it that fast?answer me i really want to know

[@CrackingTheCryptic]

It is a LOT of practice, a quick mind and fast reading skills!

[@jerichopaulespiel9873]

thank you

[@simon77047]

can you go faster? I can learn a lot if you could do this puzzle in 2 minutes instead of 3.

[@MartinLOBrien]

Thanks for this, really helpful. What software are using?

[@samcappleman-lynes6914]

It looks like the OSX version of www.enjoysudoku.com/

[@MartinLOBrien]

Sam Cappleman-Lynes Thank you

[@tomcollyer641]

Yes that's right. It was only a couple of quid and although I've only really used it to do these videos, it does feel like fairly good value compared to anything else I could find that would run on my macbook

[@abj136]

How did the center 2 get identified so easily?

[@eddieb8337]

The 2 in column 7 meant that a 2 could only go in the botom row of box 6, that eliminates the bottom row of box 5. The 2 in the middle row of box 4 means that a 2 could only appear in the top row of box 5, the 2 in box 8 left hand column only leaves a single place that 2 can go in box 5

[@MartinRochin]

@@eddieb8337 That's very helpful. Thank you!

[@eliworldwide]

how did you figure out to put a 6 at 13:50 ?? a little confused please help

[@beng2617]

yea having trouble seeing this one too

[@benjamindady4366]

Elijah Unapanta I think he’s just presuming that 4 is going to go there because of the X wing, and since the 5 and 8 are both occupied at the top of the box, that just leaves the 6... I think lol

[@beng2617]

@@benjamindady4366 wheres the x wing (sorry kinda new)

[@benjamindady4366]

@@beng2617 don't worry, he explains at 11:00 , it's the box of 4's that he pencils in. There are some other helpful vids on youtube explaining the technique.

[@beng2617]

@@benjamindady4366 i know what X wings are but I dont get why he is 100% that the 6 is in R1 C9 and not R2 C9

[@ansonyeung1420]

would you please tell me why you can put 5 in cell 51 at 9:37

[@naku--]

he was looking on the 6th line from the top looking for the rest of 2-3-8-9-7, hope you understood

[@ozertamer210]

[@isamiwind438]

what is the app's name?

[@antoniobilbylemos9918]

Sudoku

[@anthonyedwards7019]

All you guys move the cursor TOO much.

[@jill5]

The 1st puzzle has many possible results, it's not a good choice to pick and demonstrate.

[@baderalotaibi7309]

2:53 How he got 8?

[@CrackingTheCryptic]

3,5,7,1,2,9 in the same column, 4,6 in the same row ...

[@JohnStodden1]

You added a pair of 5s in col 7, rows 2 and 3. But surely you could just as easily have added a pair of 1s, and if you had you would have made col 7 row 9 a 5???

[@cynthiathornton1375]

Woah woah woah. Sue-doh-ku? Not suh-doe-ku? O.o

[@Lazy.y]

2:52 ? why did he put the 8 there? its not clear !

[@earth_is_round5649]

SE7EN because it's the only number that can be there

[@kizzie626]

becouse 4 and 6 couldn't go there

[@Lazy.y]

@@kizzie626 hehe yea that was the first day i play the game, now i can solve experts :)

[@ddstar]

looking at your notes to look like your "solving" isnt really solving

[@rowanscovell-lightfoot8750]

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