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[Music] [Applause] [Music] hello and welcome to tuesday's edition of cracking the cryptic now what have i got for you today well it isn't an 18 by 18 sudoku you'll probably be pleased to hear that um this is a return to one of my favorite sort of alternative types of puzzle um this is a star battle a three star star battle no less um and i know a lot not i know a lot of you love star battle heaven knows why it isn't a completely standard form in all newspapers everywhere but it isn't and what the world misses out on cracking the cryptic can provide now the puzzle on screen was actually uh first published back in september 2020 and it's by evan thoresby uh who has appeared on the channel before with the sudoku but we're going to we're going to take him up on his star battle challenge today he calls this skirmish in the horse head nebula and i have no idea why i've just put this into our software so i was i was thinking about the shapes and whether they reminded me of horses heads they don't the only shape that is red of anything for me is this one which looks a bit like gonzo um that shows the level of my mind um anyway before we get started with this and i remind you the rules of star battle which are incredibly simple a quick mention of our patreon page uh before we start um uh if you don't know what patreon is it's basically a site where you can join uh the cracking the cryptic club for two bucks a month and what we do is we publish a lot of extra content over there so there's extra puzzles extra videos extra solves of other puzzles all sorts of things uh we try and make it as good a value as possible and it's uh it's why we can continue to do what we do on the main channel um and i just want to give a shout out today thanks to haho who became a patron yesterday and it was incredibly generous so haha thank you very much from the both of us we really do appreciate that um now what what are the rules let's get on to star battle very simple we have to place three stars in every row in every column and in every region um and we have to do that in such a way that the stars do not touch each other even diagonally so if we worked out this was a star and i'm going to be using colors for stars today actually that means i have to make a decision don't i i am going to make my stars purple so if this was a star it it doesn't just mean you don't have stars in those positions i'll use green for no stars it means you can't have a star even touching diagonally as well so there will be no stars in any of the green cells and that is all the rules so it's an incredibly simple rule set and it's an incredibly beautiful puzzle if you've never tried one before give this a go it's i think it's three three stars out of five for difficulty so i'm hoping it's not going to be monstrous um i shudder to think the times that some of the very world's best will do this puzzle in uh people like freddie hand in fact drop us a comment freddy if you get it done in under two minutes that will be impressive probably assuming i can't do that with that if you want to play of course click the link under the video now i get to play let's get cracking and we can start with what well as i was putting into the software i did notice that column one look is entirely within one region so the three stars in this region here let's highlight the whole region all of those cells all of these cells obviously the three stars must appear in column one or column one won't have three stars so we can actually render a whole load of the grid green immediately [Music] oh and there's a little region here okay so there's a tiny region here now one of the best tips i've got for star battle puzzles i'm about to reveal the secret of star battle which is in in any two by two region like this one how many stars could we ever put in this region well the answer is one if we try and put two stars into this region like that they will always touch each other which is really obvious the moment you think about it but what it means is that for regions like this we can divide it fairly efficiently into two by two regions or approximations thereof so this two by two region you can see that would be uh well this cell can't be in that region so we could draw a two by two region like that and that leaves this domino here and we know because this region contains three stars that there must be one star in each of these colored portions and we can probably well we can do some things off the back of that this square can no longer be a star because it would prevent a star in the blue region these two squares can no longer be stars because they would prevent stars in the red region so we can do that and we can do that which is a very standard pattern that tends to come up a lot in star battles aha now the t region look at this we've got a t region here and we need to put three stars in it and they're all going to be in this column which is what's this column 16 that's this the three stars in the t region are all in column 16 and therefore there can't be any more stars in column 16. so we can immediately do that we get a star let's turn the red into purple we remove those squares um and we stop and have to think about it again so what have we now learned we have learnt that yeah look at the l region here there's an l region obviously there's got to be three stars in this l region but i can't put more than two stars into this column because that this has already got a star in it so the maximum number of stars i can put in that region there is 2 which means there must be a star in this domino now if there's a star in a domino we can do exactly what we did up here and surround the domino with greens the other thing we can do of course is that we can apply that logic in reverse because there can only be one star in this domino there must be two stars in this column which creates the three stars we need in column 17 so those squares become green that is that good for this re yeah okay it is actually look at this funny region here uh i don't really know how to describe it but if we're gonna try and divide the remaining white cells of this region into two by two regions or portions thereof this could be one this could be one and i'd actually not purple is not the color to use is it that could be one and this could be one so there are exactly three partial two by twos that we can use so that's what we must use we need to put three stars in so these squares now become green we can't put green there or it'll remove all the possibilities for the blue those become green um now let's what's that oh i've just noticed something rather good which is row 18 of the grid now i've got to put three stars in it and there's only three gaps so i can never put more than one star in this domino so there must be one in here now if there must be one in here we can do our two but our domino trick there can't be a star in any of the squares above it which places a star in that cell which places a star here we can now ring all of this in um in green we know there must be stars in those two cells so we can place greens around those so far so good with this one um okay so now we've got right okay now we can do oh in fact i could have done this logic before couldn't i sorry i'm just looking at the perimeter of the grid and noticing there are only three regions in the perimeter so that means i need to use the nine stars in those three regions to provide three stars in every well in row 1 row 18 column 18 and column 1. so several of the stars need to do double duty in fact three of them need to do double duty and one of them can't do double duty because you can't put a star in this corner so there must be stars in the other three corners in fact i've got two of them so that must be a star up there and that's going to allow me to put two stars in here then there's one star in here one star in here two stars here and then it's working nice [Music] um yeah okay now i'm tempted actually to look at these two columns because you can see if i look down here i've got to put a lot of stars into this real estate you've got to put i've got one star in this in column 17 i've got to put six stars all together in columns 16 and 17 so these cells here have to i have to put five stars into them so let's see if we can do that one there two there three there ow it's not bad but it's not perfect that's we know there must be one star in each of those colored regions there but you can see that's not actually developed our logic any further [Music] okay so what do we do next we can i'm not terribly happy i can i can delineate all of these regions the black lines are a little bit a little bit weedy aren't they i might put a couple of links under the puzzle therefore in case anyone finds the it a bit difficult to see this region is quite small um but that can still you know if again i what i'm noticially doing in my mind here is dividing it into two by twos one two three four so there there is license with that one i've got to put two st ah hang on yeah look i've got to put two stars in these these yellow cells at the top so i can't for example if i was to put if this square was a star it would rule all three of those out and i could only put one star in the reach so that's definitely green and therefore this is green as well if this was a star it would rule out those three squares i'd have to put two stars into just two cells so um once so now okay so what does this mean i've got i've also got to think about this region so the thing the reason this region has caught my eye by the way is this string of cells here i can't put i can't put three stars into this region because there's already one star in the row oh look there's there's stuff going on here actually there is stuff going on because i've also got to be careful about this column i don't know what column number this is but it's already got two stars in it one two yeah okay so we can prove this square is not a star let's look at this square and think about whether it could be a star if this square is a star the r the red region next to it has to have a star here now which completes the three stars for this column but we've now absolutely broken this region because where can we put the stars in this region around it now we can't looking at the purples we've just put in there couldn't be stars in any of those cells we can't put a star here because that would be a fourth star in its column so now there are no stars in those cells which means there have to be three stars in this run of cells here and that puts four stars in row two so all of that means that this square here is most certainly not a star and therefore its other one must be a star that gets rid of some of the stuff at the top oh and in fact now i've only got three stars left or three cells left to contain two stars in row one so both of those must be stars which is lovely because that means they aren't stars that means there's definitely a star in this domino so we do our domino trick rule a star out of these cells and now this this shape is even more restricted because i can't put two stars into this region so the question to ask i think is can you put zero stars can is it possible in fact we can put some greens in there anyway is it possible there are zero stars in here if there are zero stars in here i have to put three stars into those cells that's definitely not possible because then i couldn't put a star in the red so there must be a star in here i'll make that orange therefore to indicate one star in that region therefore there must be two stars in these cells and again we can't put the two stars into those into here and here because that will rule out a star altogether from the red so there must be a star here and that completes this column so this is not a star this is a star this is not a star this column let's surround the purple and complete the column you can see that's going to do work at the bottom as well gives us a star here gives us a star here this column now has three stars in it turn all those green um turn them green popular tube station uh now i need one two i need a third star in this region it's got to go there put some greens around it this row has got its three stars all right albeit that we don't really know where this one is but we do know it's not there lovely absolutely lovely and not so far not brutally difficult um so where do we go next we can where do we go next we've got right looks like we can do something with this region now because there's more constraint on it than there was the maximum number of stars in this region i've just drawn in there these four cells is one because i've already got two stars in the row now if there was not one in these there'd have to be three in this region which is impossible so there is one in here but there's exactly one so we'll make that red actually no i'll make it blue because it stands out a bit more from the orange there must be one in this region and one in this region and therefore we surround it again using our domino trick [Music] we can complete the rest of this row in green because if we've approximately placed the three stars and we can okay now we are now it looks like it's going to get tricky again doesn't it so we've got to think harder let's wind up my brain um ah this column has got two stars in it so there's only one star in that string of cells okay right now that's very interesting because now if you look at these cells we're going to have to count this but i just want to show you the regions i'm looking at i'm looking at these three regions here it's really it's a bit difficult to see but there's one region there looks a bit like a snail um there's this region which looks a bit like an f that's been turned around and plonked down on its side and there's this region which sort of i don't know what that looks like a squiggle those three regions there need to have nine stars in in them obviously three three regions three stars a region nine stars but we've just drawn a dirty great hole right in the middle of this where this those cells can have no stars in them at all and this string can only have one star in so in the rest of this that region plus this region i've got to put eight stars now that seems too many um let's just see how many we can put in we can put one there two there three there four there five so there's a maximum of five in this shape so i need to i need to put at least three in this region oh this is not this is lovely i need to put at least three stars in this region well how am i gonna do that um you can see i can put one in that region let's make that blue i can put one maximum in that region and i can put one there and that's that so you know i have no latitude this will have to be a star let's make it purple and surround it therefore in greens now we know that this blue domino needs to have a star in it so there's no star below it there in that domino which places another star make that one green just checking the columns yeah because look this column now this column here i don't know what what's it going to be column 15 i think that's got three stars in it so those those those and those all turn green which means we can fill in a lot more stars so those two have become stars and then we can fill in more greens to complete the column we've created a domino of blue there so let's surround that with a couple of greens okay i can't see what else to do there we can probably do more if i if i get more brains um i can't see how to do that but we can do more in this shape this has got to be a start so let's put that in and surround it with green that gives this red domino here needs to be a star in one of those so we can green those which creates another star at the top surround the star with green this is going to get tricky now this is going to get tricky because i know that there's a star in this red domino and therefore i know there is no star in these two cells but when i take those out i'm disconnecting my orange region so now i've got to remember there's one star in these orange cells here i think i can remember that i think i will i will wing it um oh no hang on hang on i might not need to wing it because the f region how many stars can i put in the f region at all one i've got in i need two more well i can't put more than one in this domino and the only other cell that can be a star is this one so this is a star let's make surround it with green i know one of these two is a star now so this becomes green and this becomes green oh no that's just disconnecting my oranges even more um so i know there's a star in one of these two oh but hang on am i miss counting this or have i got three stars now i've got one star two stars three stars in in the snail region so i don't need any more stars slightly disconcerted by the outline the black outlines of the region but that definitely looks like it's like that to me so i don't think they can be stars that means this is a star this is a oopsy that's a star this is a star and this is a star in order to keep the stars apart the rest of it all becomes green we've now got a whole variety of stars in this region um whole nebula of stars [Music] okay can anyone see what what it means uh i'm sure there's a way of seeing what it means i just don't know if no i can't actually see anything immediately good off the back of this although it did feel like that was a really good series of deductions so ah but maybe i can use this region it's a slightly dull region this to describe but it's this one now the top row of it must have a star in it because if it doesn't i have to put three stars into this uh sort of large domino and i can't put three stars into that shape because there's only one two by two and one domino in it so there must be a star in this string of cells which means the rest of this row cannot be another star which removes stars from these two cells and plonks a star in here which plonks a star in here which should do quite a lot of work i think we can now ring everything in green that's not star there's now one star there ah but look column uh 17 has now got all its stars in it so that's green all these turn green this is now the style that's a star and that must be a star and we've now so actually this has gone remarkably well now done i've done all of these columns i need a third star in this region so that's a star now look along row one four of the grid i've got one two that's a third star so these two turn green that becomes a star complete the column with the greens sorry the row with greens because we know approximately where the three go and do the same with the orange region here those two have got to be green now let's turn our attention to this sort of large rectangle because we know we've got to put two stars into this so this neither of these cells can be a star if either of these are a star you can only put one star in the region so those are green we'll make those red or make these blue which means these two turn green once oh look yeah this is interesting in the in this uh red and blue dominoes now if we count the number of stars in these rows we've got one two three four five six which is exactly how many we need so those and those have got to turn green that we've got the three stars in this row all of these turn green i'm heading down towards the gonzo region um maybe actually i can do something with gonzo you can't put a gonzo can't have an eye if gonzo has a star in his eye there you'd ring all of those squares in green and you could only put one more star in gonzo's beak or whatever gonzo is does he have a trunk i don't know what even what gonzo is but you know what i mean this is definitely green um okay so now let's have a look what have we done have we got how many oh hang on a minute how many stars have we got in this region not many is the answer in fact in fact the answer is none i've not put any stars into this region yet so i've got to put so there must be a star in there there must be a star in here and there must be a star in there which means we can ring that with green that gives us three stars in this row so those two those two turn green that's therefore a star these are not stars there's no stars here we've got three stars approximately placed in row six so that's not a star two three and okay and now we pause again while we take stock we can what can we do the answer is i don't know oh although i've got another massive region ah look look look look look this strange region sort of going through the grid here is another region i've not put any stars in but i've got one hole there a domino there and one hole there so each one of these musk each one of these holes must contain a star so those are definitely stars surround them in green and this domino here needs to have one star in it so that becomes green and that becomes green right so now look i've got two stars in this row which means all of these squares can contain a maximum of one star which means i have to put two stars in this region into this run of three cells so they must be in those two positions we can therefore do that must be close to finishing this now i think um this star is seeing that cell so we can finish off this one that gives us three stars in this column let's finish that off with green one two we need a third star in this region fill that one in that removes those two squares from being stars we place a star here that gives us three stars in column six so these cease to be stars all of these cease to be stars gonzo has now become incredibly constrained um [Music] yeah in fact maybe that's the easiest way to crack this at this point let me i'm just having a stairs to see if i can see anything really obvious but oh well no it's not really obvious but no in fact it's not obvious at all but these these two columns here i've got to put six stars into these columns now how many can i put in one two three four five uh oh and that could be one or that could be one no that's completely useless okay let's look at gonzo so gonzo's beak has now been ruled out from having a star in it so we've got to fit three stars into the rest of him well that could be one that can be two and this can be three and therefore we can remove that one but by the domino rule which places a star in the corner of gonzo this that doesn't actually seem to do anything well it gets us some greens though let's put greens around him ah now look column one and column two need two more stars so there must be a star in that region and there must be a star in this region but there can't be this is great there can't be more than one small star in column one and we know it's this one so these two squares are not stars which places a star here that means this is not a star that means this is a star which means this is a star and i think that might be the final piece of the nebula so to speak i've got all my stars in this column get rid of that one i need three stars in this column so that's got to be a star now which means that is not a star i've got three stars in the row i need three stars in this column and i've got one two which means this has to be a star which means those are not stars this star sees that one i think that's been there for a while sorry i could have done that that fixes another star here three stars in this row that fixes that this one isn't so this is a star this is not a star this is not a star we've got three in the row oh goodness i've got to put three stars in this row i've got nothing in it yet so that must be a star that can be that must be a star that must be a star that finishes off lots of stuff there we go so this one that look can't be a star now i'm hoping if we look at this region one two yeah i haven't i don't think i've put three stars into it i've got three in gonzo one two [Music] yeah this must be the last one that comple yeah in fact look row row 17 was the easier way of looking at that therefore this is not star and this is a star and i think that is the complete solution to thorsby's puzzle very very nice star battle for a change i hope you enjoyed it i hope you enjoyed the change of scene i do enjoy doing a different type of puzzle every now and again but only if you know i'm assured that they really are superbly good and this certainly seemed to me to fit the bill so thanks very much to thorsby and yeah i think it looks right and um yeah we'll see you later on for another edition of cracking the cryptic