A Sudoku Puzzle That WILL Improve Your Solving!

[Music] hello welcome back to cracking the cryptic where today I'm actually quite excited to cover this puzzle this is a puzzle that I found hidden in the depths of Nicola calm by the website that unfortunately tragedy but it's closing down and I actually believe that this puzzle might be the best tutorial sodoku I've ever seen there is something in this puzzles logic for even the most advanced solvers and and it is a beautiful solve so what I want to do is slightly different video so we can try and learn from it as much as we can so we'll do the simple numbers first of all and then we'll go from there and I'll I'll hint at where I think you need to think about the next piece of logic and we'll try and solve it together that way so without further ado let's look at it you can see we have a 3 here a 3 here so this where here that's going to have to be a 3 well we can see we have a 6 here on a 6 here so let's put a 6 into this block it gives us a 6 here as well this sixth missed 6 ok this this 5 here see that will allow us to pencil mark two fives in this block fives and we forced into one of these two positions and that allows us to place a 5 there as well scanning the column column brought one here we've got to place 5 7 & 8 see we have a 5 here and 5 here so this square here will be a 5 and then have a quick look at this middle 3 by 3 blocks if you can see something interesting about about it so I'll tell you now we need to notice this 3/4 pair and this 3/4 pair now that's going to force a 3/4 pair into these positions which immediately actually allows us to place a five here again look because there's now we have a 5 here 5 here 5 can't go in this position so this will have to be a 5 allows us to place a 5 there and 5 here that resides it 5 there so we've done all the fights and you may be thinking with us that's like a very straightforward puzzle Simon let's see one thing we have to remember about Nicola puzzles is that they're all hand design so I mean this this puzzle has an author you know the author is not at the computer program so and what you tend to find with these puzzles therefore is that they do have a beautiful internal logic it will have been designed very carefully to ensure that there's a linear solution path that you're intended to find if you study it for long enough this is an extra hard puzzle too so although we've got all the fives there is going to be a sting in the tail now one thing we can notice here is this 7 and this 7 and you can see that rules out sevens down the column here rules out a 7 from this square so that allows us to pencil mark sevens into these two squares and this I think allows us to spot a very common thing that you find with this sort of notation in in Sudoku solving but it's a nice example of it so we you need to think now about where we can place a 7 in the first three columns and you know using the information to be gleaned from the sevens that we already have placed in the grid and the critical thing to note is that the seven in this 3x3 block is locked into one of these two positions and there is a symmetry with where the 7 is going to end up in this 3x3 block here in particular it's not possible for 7 to be in row in column 1 in this 3x3 block it is going to be in one of these square squares which are in column 2 or 3 and so it's the 7 in this 3 by 3 block now you can play around with the sevens as much as you like but you won't be able to place a 7 therefore in any of these three positions here because if this is a seven for example the seven in this 3x3 block will be locked into one of these two positions and that will rule out sevens from all these three positions this is a seven that will force a seven here that'll do exactly the same thing so there's actually only one place left that a seven can go in this 3x3 block and that's there that allows us to place an eight as well okay and now I think the first bit of more difficult logic so we now need to hunt we need to hunt for two x-wings hidden in this grid and pause if you don't want me to tell you the numbers we want to look at numbers we want to look at fours and sixes so take a stare at the grid and see if you can work out where these x-wings might need to or where they're going to exist now remember with an x fin what we're trying to do is to isolate two positions in a row or a column where a number can appear so let's for example let's just take a look down column 9 of the grid ask my cells where we can place a four well you can see can't place a four and either of these two positions because of this for this floor over here rules out a 4 in this position this position can take a 4 so let's print some marker for their and so can this position for here now if we move across an outer column 6 and ask the same question this four rules out a 4 into any of these positions is same for over here that we looked at before rules out of four there this can take a fall and so can this so we have this box arrangement of fours now I'll try it out some highlighting and what that means is that we were looking at the columns that we were trying to identify where in these two columns force could go but by finding this pattern of force we rule out there being any other force in the rows that these fours are occurring in so there are no no more force in either row 6 or row 9 now one thing when you find an x-wing especially in a handcrafted puzzle is probably not going to be by accident so we need to we need to stare at the grid here and ask ourselves well which which cells are affected by this logic that we found and there aren't many actually because before here is already being ruled out by this four so you know the fact that there is an x-wing doesn't really help us for this square it helps us for this square we couldn't have ruled out a 4 from this square without the x-wing can't help us rather of these two squares because this four is already eliminating force and it can't help us for this square because this square was already eliminating a four here so it's only this square as well so there are only two squares really that this x winner for is helping with and that might allow you to sort of try and hone in I think I said I've already told you that this 6s we need to think about as the other x-wing that's hidden in this grid but what we're trying to probably do when we find this first base piece of logic is to find a second piece of logic that's going to interact directly on one of these two squares now let's take a look at sixes in column nine here we have a six here we don't have six and six could go here this six is ruling out sixths from these two positions this position here can take a six let's look now at it can't five looks hopeful actually you can see again this six is preventing a 6 from this positions we have six here no 6 in either of these two positions no 6 here and 6 here so now we've got another x-wing now on sixes and you can see this six this arrangement this x-wing on six is it's not having no effect on this square but it is having an effect on this one so I would suggest that this is the next square we need to try and pinpoint whether this square has a weakness so what numbers can go into this square well on the face of it one can go in two and three cards for can go in because of the x-wing five can't go in six can't go in because of the six x-wing 7 can't going eight can't go in and nine can go in so it looks like it can take a 1 or a nine but look at this one here this one here allows us to place pencil mark ones into these two positions and that means this square only has one more possibility this square here has got to be an ID once you know allows the pencil mark nines there look and some up twos into those two positions and now it's a really I think this is I don't see this piece of logic very often it's very obvious once you think about it but it some reason my brain just doesn't work this way very efficiently so let's have a look now at this 3x3 block and ask ourselves about whether or not there's anything important about the numbers that's it that can go in here in the arrangement of those numbers especially considering the 7-9 pair that we have down here so it's obvious that 7 8 & 9 can go here and this 8 is for senior 8 into one of these two positions but it should be clear to everybody that the eight can't go here if the eight if the eight is here these two squares here both of these two squares will have to contain the numbers 7 & 9 if that's the case this square could not be filled because we know there's a seven or a nine here well if they're these two squares are 7 & 9 there's nothing left to place here so in fact this square here has to be a seven or nine because if it isn't and it takes the eight we run into the problem now that means this listen eight here this is a seven or nine there like that now what we do now sevens in these two positions so there's a seven in one of these two positions here and we get this this symmetrical arrangement of sevens now as well in column in rows two and three now so we know the seven here is locked into a either row 2 or row 3 in this 3x3 block same thing here it's locked into row 2 or row 3 so there's going to be no sentence in these four positions here 7s are forced up into Row one and we have a 7 here so allows us to pencil marks tones into those two positions ok now look at column 9 and ask yourself some questions about column 9 there is a really interesting this is more of a New York Times type trick that we're going to see here so you can see we've got eight five one and seven in the column already but in row five and Row one we have the number six three and four none of which are appearing in column 9 yet we've got eight five one and seven so we've got three unknowns here being ruled out from this square and this square to open positions in column 9 well if that's the case the number six three and four must fill the other positions in column nine in order for it to work so we know in fact that this is three six and this you know three four and six are going to be down here like this now we've already got a three here so you can eliminate that three and we've already got four here so you can eliminate that four and eliminate this 6 so 3 4 & 6 so the numbers were left with placing therefore r2 and nines in the open positions so it's not a pencil my baton that's me now into 9 okay so now how can we use I see yes okay so now let's have a look we've eliminated this square now down to a 3 or 4 and that match is very nicely with this square here so now 3 yes yes I see ok so now let's take a look we're looking for another x-wing here this time on Three's and we need to somehow use the fact we've just found this 3/4 pair so that gives you a hint that we must be looking at one of these two well at this position in particular is the fact that we've managed to eliminate a3 from this position must be important so let's have a look at column 8 and ask for cells where a3 can go now so can't go in this position because of this three can go here Kengo here can't go here now can't go here can't go here so there are two positions for 3 and column 8 now let's look at problem for no yes no no nope so here another X being hidden in the puzzle all because of this 3/4 pair and now that must be useful surely that's so we're now let's have a look at Row 3 we need to place 2 3 6 7 9 well threes are ruled out from here now 2 3 6 seven is ruled out because we have fact will you manage to get this seven here this has to be a nine there we are so an another beautifully intricate number that we've had to sort of farm from this grid format now this oh no no no no to do that sorry put a seven in there like that and now I think we're probably closing in on the final stages but I think you'll agree with me I hope you'll agree with me this has been a very very tough challenge this one here and this one here mean this has to be one books up there ones in their minds now I've forced up for that position that gives us this - that means this is a - here - in one of those two positions - here - one that way around must be a one it's just got to be an eight okay and I think I can leave the rest of it for it as an exercise for the viewer I really hope you enjoyed this puzzle I thought I thought it was sensational to be honest we normally look at the diabolical from the Daily Telegraph on Fridays over the weekend and I I did have a look at it this week and it really it had none of the beauty of this puzzle so I think this is definitely a better a better puzzle for teaching us all more about how to salsa Doki better so please leave comments please subscribe to the channel if you enjoy the content we really appreciate that and we'll see you again soon I'm cracking the cryptic you [Music]

Channel: Cracking The Cryptic

Views: 56,538

Rating: 4.6094275 out of 5

Keywords: improve your sudoku, improve at sudoku, sudoku tutorial, sudoku techniques, x wing, x-wing, sudoku x wing, hidden triples, sudoku tips, sudoku tricks, how to solve a sudoku, learn to solve sudoku, expert sudoku lesson, expert sudoku teacher, sudoku genius, simon anthony, mark goodliffe, nikoli.com, sudoku puzzle, sudoku explained, sudoku method, sudoku methods, sudoku class, sudoku school, best sudoku puzzle

Id: XRfFPaUxTfM

Length: 17min 35sec (1055 seconds)

Published: Sun Oct 21 2018