Techniques for Starting Hard Sudokus

[Music] hello and welcome back to cracking the cryptic and to today's bonus content and going back to classic sodoku today we've been sent this puzzle by Garry McCarthy who is a viewer who recently became a patron on patreon so do check us out for the extra content there and there's always some stuff going on and you're very welcome to kind of help us support the channel we may also be slightly more likely to try puzzles and we do get sent an awful lot though so there's no guarantee for anybody now this puzzle I don't know where it came from Gary had taken a photo of the puzzle that he had written out by hand so I don't know where it's come from what who the compiler is or what the source is so who knows I don't know what the puzzle is gonna be like either as I said Gary said he didn't make much headway with it so let's see how we go you can try the puzzle yourself before watching a solve of it it's on the link below the video to just click on that and try it in our software but for now I'm just gonna carry on and get cracking and see how we do so I've got some ones down the side so I'm gonna mark in this box where one has to be in one of those two cells the normal Snyder notation that we use those sevens restrictive as well a lot of common numbers amongst the various shoots of 3x3 boxes actually in fact apart from fives I think I've found them all there so fives from one of those - crikey okay this is I mean tough to start is I think the theme here [Music] ates are restricted to one of those two cells and down here because of this eight which rules out those three that is and that eight the rules out of those two now the same eight up here is ruling out that this one's ruling out those two so one of these two has to be an 8 as well 9s doing much the same thing to this box but in two different cells we can pencil marker nine new crikey there's not a lot to go on is there so now I mean I think it may already be time to 904 okay four is a bit limited here so we can at least drop that into one of two it's not getting us very far I mean we're gonna have to look for candidates in cells I mean I noticed wait and it's one along the top that I only had two Possible's this one can only be 7 or 9 for instance but I don't think that's very useful or maybe cells that feature to get our look yes there we go okay we've got a 3 & a 9 in the same column there and a 9 in the 3 in the same column there now that's ruling out 9 and 3 in column 8 twice and look at this 3 & 9 that's ruling out nine and three from can't get there from all of those three so in row eight I may have said column 8 sorry in row eight nine and three is now prevented from being anywhere except there and there and that well it is a useful double I can see that immediately because of these sevens eyepencil marked it so at least that is giving us a seven over here because seven obviously can't be in any of these other cells in row eight so that's good - yeah - is ruled out from sorry about that hang on a second poor controller my keyboard there we go that's better okay - is ruled out from those cells and those ones so - is now definitely here actually as something I should have probably spotted before that - was limited to those two places but anyway got there in the end so that puts a two in one of these two now one that's been resolved so we can put a one in here three three is ruled out there and we know it's a candidate for this one but that doesn't mean it's in that cell it could be in one of these two but that puts it in this cell so in in column seven there's only one place left for a three and it's got to go in there that gives us a three in the central rocks I'm sorry about the right-click menu that keeps coming up at in a white it does three there in one of those - interesting now what else is that giving us because I think this has been helpful nine is restricted to one of those two because it can't be here or here in the column two is obviously in one of these two how about this row with the forced three nine four five seven two no nothing much there hmm thought we might have got just the key breakthrough there but there may be more to do here which isn't that surprising as it's a difficult puzzle let's keep going prove the fours or the fives is this three more help for the night somehow figured out six three two nine five plus seven that's what one or an 808 looking into this box and ruling out three of the sales so eight is now that's good yeah eight now and one of those two that means this can't be an eight so we can put eight in here eight in here because this can't be an eight and that gives us nine which had to be there or there must now be here that's fixed our nine three pair that gave us the whole breakthrough excellent so eight is now restricted to one of these two nine is in one of them nine is here because nine is ruled out of two of the cells of this box so knowing is a definite there oh six eight three there seven nine five here and it's giving us a triple of one for two which are 1 2 there 2 for there on for one there can't disambiguate those but I can put a 9 in the box now that's got to be there these two must be a double 3 6 the remaining 2 in that box of 5 and 7 in some order 3 3 that's available for some time so threes in there we've got a pair one-sixth and I want to call it a double a moment to go in there this has to be for in column three this is five seven kind of part of a five seven pair there haven't got any more from that in fact whatever that is has to be this say it sorry has to be the same as the top one there now down here surely this is a four six pair obviously over here so this can't be and it could be it's gonna say it couldn't be for our look yes four four there is ruling out those three four there and they're rolling out those two so in the top right box that's our four that does sort out the six four pair so I can take four out of that so I'll put it in here we can finish off this row four and five that's meant to be this is either one or six that is quite interesting because whichever one it is is us as well as being ruled out of those three cells whether that is 106 106 must be ruled out of all of those cells in the center box because there's a six and A one looking into the middle row as well so this must be the same as this which is one or six now I don't know which one it is but that's an interesting find I don't know if they'll actually help us but interesting now for is one of those two - oh yes this is a two five pair now so take two out of the corner and we've got eight seven six to fill in there don't know which way around they go yet we might have to do a bit more at the top so five is in one of those - mmm ah okay the other thing about that six and one being ruled out from there is that one of these as well as this one one of these two must be one or six forming a pair with that and meaning that these three at the top can't be one it can't be six either although that was more obvious it's interesting that they can't be one because that one's ruling out some more sales from that box and leaving one just to be in one of those two which is great because combined with that one we can now place one in this box up here that's quite lovely I mean I've quite odd I have a feeling I've missed something else to find that but never mind it's quite nice to the top has to be in this cell in the top row that place is a two down here yeah that means six has to be in one of these two cells let's just get rid of the two in the corner there six has to be in one of these two cells so we use the corner notation to show that that's helpful because with six here we now have to play six in one of these two cells in column 4 and this one decides which one so that is what resolves whether that was one or six we remember that whatever this was had to be the same as this and therefore it's six this is now let's take out all the corner notation this is a one eight one eight the spare has been resolved this is now a naked single four eight six five - seven the column three one in the row we can put in a nine we've got a pair up here that's three and one effectively we've resolved where the one goes because one has to be limited to all of those cells well actually one is in one of these so I'll put that in that resolves the eight one pair and now one there one in the central column so one is here that gives us the three containing that one out of the corner yeah this is a nice puzzle actually six and three a resolved by that three and closing in on a finish now where does 6 go in column seven it's got to be here six two four one nine three that's a five seven for the pair so that's the eight one of these is eight I don't know which whoops don't know which one yet six has been ruled out of those two so six can go in there eight and seven is up there there let's take a down at the corner yes that's sorted out there five seven pairs that are happening everywhere so 7-5 7-5 lovely so we've got seven and nine in those two eight and five here and we can fill them in now and nine and seven at the top that's resolved in seven a pair that five fixes the two fine if over here and we must be finished in the one for to triple lovely one more triple down the center it's one four seven there they go so nice puzzle thanks for sending that Gary that was quite enjoyable I hope you've learned something from that I mean basically when you get stuck you've got to try and find some useful candidates for doubles or triples I think I mean it's that's one of the techniques and that 3:9 pair along rowing really unlocked this one well done if you spotted that well done if you spotted it before I did that's workers I wasn't unhappy with that one so thanks very much for watching do stay with us on cracking the cryptic please subscribe if you haven't already although I have to admit subscriber numbers are through the roof fantastic and do watch out for simon's video from earlier today if you haven't seen it already it's on a cracking puzzle and thanks very much for watching hope to see you again soon and bye for now [Music]

Channel: Cracking The Cryptic

Views: 72,694

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Id: jN6jveTebHw

Length: 15min 29sec (929 seconds)

Published: Mon Apr 27 2020