How To Ace The New York Times Hard Sudoku

[Music] hello fellow crackers and welcome to Sunday's edition of cracking the cryptic now today we are going to be on classic Sudoku and we get a lot of requests actually every week about the New York Times hard sodoku and we haven't done one for a while and we've got an unusual number of requests today so we are going to do just that we're going to have a look at the New York Times hard today Q which is unscreened in front of you now the New York Times you can get this puzzle on the New York Times website until midnight tonight u.s. time at which point it will disappear forever they don't have an archive so I put it into our software and you can obviously if you're watching this after the 19th of January you should just click on the link under the video that will take you to our our software where you'll be able to play the puzzle what to say before we start this or firstly another question we get asked a lot is about the New York that's about Sudokus in general and which ones you should be doing well of course you should be doing the ones that appear everyday on cracking a cryptic but if you don't do those and you're looking for sort of some standard fare you can do in the office when the boss isn't looking then I think the New York Times hard puzzle is about the best out there it is computer generated which is something I wouldn't normally recommend but it is the algorithm has been reasonably well put together frankly the puzzle is generally fair it doesn't involve silly techniques and it represents you know a decent a decent sodoku now the only thing I do find amusing about New York Times heart puzzle is that it has a proclivity to use one particular trick and the trick always appears at the very start it's a clever trick don't get me wrong if you haven't seen this before you will like this because I've seen it a piece in this one but it does rely on this trick to ramp the difficulty up and the interesting thing about the tricking question is that it fades standard technique quite well so if you are a follower of the channel and you use the pencil marking method that I recommend that won't help you very much with the New York Times have a puzzle so you have to get good at spotting what I'm about to show you now let's take a look at the grid now what you have to look out for 3x3 boxes in fact like this middle box that contain exactly three digits now you can see there are lots of them in this puzzle so we've got five different 3x3 boxes that have three digits in it now if you look at this one thing that is surprising is that in the New York Times it's quite rare in my experience for their numbers to be arranged like this they tend it tends to really like putting them such that there is an open flank within the 3x3 box so you can see in every single one of the cases in this puzzle for example the 3x3 the three numbers in their 3x3 boxes are arranged such that if we look at each one of them there's a line of three they're completely unused a line of three here and here here and here here and here here and here now this is important because let's look at this central 3x3 box there cannot be a 2 5 or a 9 in any of those three squares now in column 4 that is absolutely huge because look we already have three digits in column 4 and they are not repeating any of the digits that are appearing in the central 3x3 block so where can the numbers 2 5 & 9 go in the set in column 4 well there are only three possible places those squares there these are the numbers 2 5 & 9 now this this is a massive the important suppose break through in terms of cracking this puzzle because let's imagine now we didn't know this and we were focused on two fives and nines and we were trying to pencil map them how far would we get so let's look at this box can we pencil a 2 5 or a 9 well yes we can pencil fives into those two squares that is true we can't pencil nines we can't pencil twos down here we can pencil nines into those two squares that's it so there is very little way for us to get hold of the fact that there is a hidden triple in column 4 by using standard technique and this is why this trick is effective and it's why if you learn if you learn about it it can make you a much better solver so always with the New York Times check these situations and check them at the very start because if that never develops into one of these positions it's always there right at the beginning now having said that let's see what we can do so let's actually put the 2 5 & 9 in just going to quickly check the rest of these triples to make sure that we're not missing another one sometimes there are two I mean it's not quite good enough but you can see for example if we look at column 8 here the 1 4 9 in this 3x3 box now means that these four cells must include the numbers 1 4 & 9 so another thing New York Times tends to do on occasion is if we look at this row for example imagine that rather than these two being a 6 and then 8 they were a 1 and a 4 then we would have a 149 triple in this row and combined with the 149 triple in this box we would then know that those three squares would have to be the one four and nine in column eight so that's another thing another way that this trick tends to manifest itself but anyway enough of that let's actually get this puzzle done so supposed to 5 here so that's got to be a 9 that can't be a 2 or a 5 let's get rid of those options there so 9 9 oh now that's got to be a 9 obviously just checking the nines here these three squares have got to be one three and four to complete the column that can't be a 3/3 actually as oh three is very restricted in this box that can only go in this square so let's put that in that mousse that means that's got to be a three in the center gives us a 1/4 pair must be a 3 in one of these squares six here that's these sixes interacting fours look in this bottom box now this is a four now again it's worth noting I wonder if this is why people have had trouble with the puzzle if you didn't know this was a 2 5 9 triple you could have pencil mark falls into those two squares but you wouldn't have been able to write this for in so it could well be that this this initial trick is why the puzzle was proving recalcitrant ASIS yeah 8 so important in this box can rule out eights from these squares so that's gonna be an eight lots of four we now know there's an eight in one of these three positions but I wouldn't pencil out that I like to pencil mark where a number can go in exactly two positions in a three by three box unless I'm doing variant sodoku mark on the other hand would merrily pencil mark eights into these 3 squares especially for who is solving on paper but it's not something that I do one here means this is a 1 that means that's a 1 because we know this can't be a 1 so these three squares have got to be 2 5 & 7 to complete the box that one can't be a 5 that one can't be a 7 this has to be a 3 so what we need here 2 5 & 7 again so that's a 5 or a 7 that's a 2 or a 7 Nine's one of those two squares has got to be a 6 I'm coming back to the central 3x3 look we've got a 6 and an 8 on the left on the left hand side so this square can't be a six or an eight these two can't be a six or an eight so these two squares are a six eight pair which means these two squares are a six eight pair this square must be a seven that means that's brilliant that means that's the - that's of live and that's a seven that means that's a two which means this is a 5 just unwinding the pencil marks nothing clever about any of that the square at the top to complete this column must also be a six or an eight - you too - must be a two in one of these two squares the other ones gonna be a seven these two squares have got to be six and eight so we can't yet identify which way round that goes suppose it gives us a six and an eight in this column though so we should keep an eye on that for ah look there are seven and a nine there and a seven and a nine here so that interacts rather nicely on this box where can the seven and the nine go only in these two squares so it's a pencil mark that in this square now has to be a nine because of the nine down here now this is nice look nines here and here so I'm going to get a nine here and this is the advantage or one of the advantages of the pencil marking the moment I place this nine I also can place the six one of these squares is a nine this must be a tour of five to complete the column oops - five four four six eight this square looks like it can only be a five to me because and again this is good technique I guess getting good at comparing the contents of rows with the contents of columns so here my eyes flash up as I tend to read this way I tend to read rows first rather than columns first but as I'm reading the row I'm scanning down the columns and looking for gaps and I can see that these three squares or these three numbers have not appeared in these five numbers three plus five is eight I know there are nine digits in any row in a Sudoku so I know this is the missing one so that's a five five in one of these two squares now what I should have done is not pencil mark six mates into those I was about to wonder about that that's going to be fives and eights which could be resolved of course that would help the other thing to bear in mind is not to miss miss pencil mark your puzzles because it makes you a lot slower one two and four into these squares before that's got to be a one two and A four as well five five two four Oh No choose this can't be at two now the two here means that this square can't be a two so this has to be a two that means that a five out of seven and that or two now this must be a seven look for here means one of these two squares is a four so one of those two squares is of four need a 1 and a 4 off to complete this column so let's pencil mark that in and just see if we can this must be a 5 I can't be a 2 that can't be a to either 2 is in one of those two squares yeah that square look again let's just practice this so these four digits here are not in this subset of digits in the row especially not if you include the four so the four pencil marks are the easy thing to miss here but with the four pencil marks what can this square be it can't be a two for many reasons but let's look at that reason that's what I saw three it can't be a four it can't be a 5 a 6 a 7 and 8 or a 9 so it must be a 1 so this must be a1 therefore that's a four that fixes all of these one Falls have dotted around the grid look this two is going to be nice because it's going to make this a seven this of three and this or two now there's three points of these pencil marks and fixes the three over on the left-hand side that squares got to be an aid to complete its box now that's an eight in one of those squares this should be a six I think resolves the six and the eight seven results the seven and the nine this nine resolves everything in the top row look of the six six and the eight here so we need one three and eight into these positions so one eight three and that's how to do the puzzle so that's the New York Times puzzle today and as I say I think the reason people will have had trouble with it is this initial step some massively is it massively nice thing actually and the New York Times gives you ample opportunity for practicing spotting it so I hope you got it done we'll be back tomorrow another edition of cracking the cryptic [Music]

Channel: Cracking The Cryptic

Views: 82,031

Keywords: new york times sudoku, nyt sudoku, hidden triple

Id: UGDnLIFdSkg

Length: 17min 10sec (1030 seconds)

Published: Sun Jan 19 2020