This walkthrough elegantly demonstrates the power of deductive reasoning through the lens of Kropki Sudoku. It is a refined and satisfying watch for anyone who enjoys systematic problem-solving.
Deep Dive
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Deep Dive
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Hey, how's it going? Welcome back to the channel today's puzzle which is called Bandy Bandy by Hugo Bob. I The name sounds really familiar. I can't remember though if I've done a puzzle by them before or I've published a puzzle by them before. Um I did look back. They've done like seven or eight puzzles I think this stage but I just cannot remember right now whether or not I've done one of their puzzles but I'm going to look at this one. It looks like it's fun. It's not supposed to be too difficult which is good for me right now cuz I'm not feeling very well.
If you notice my voice is probably not sounding the greatest in the world but uh we're going to try to get into this one, get it done and um have some fun doing it.
>> [clears throat] >> But I can't get the brain thinking too hard today so we're going to try to do something a little bit of it on the easier side uh which is perfectly good.
So anyway, it's called Bandy Bandy again by Hugo Bob. Let's take a look at the rules, see what's going on here. It's called normal It's called It has normal Sudoku so every row, column and 3 by 3 box will contain the digits 1 through 9 once each.
And then we have crop key.
So digits supplied by a white dot are consecutive so these two will be consecutive and then digits supplied by a black dot are 1 to 2 ratio where one digit is double the other. So that would be these two.
2 4 3 6 just some sort of uh grouping of digits where one is double the other.
That's it. So with that said, let's dive into it. Link is going to be in that description below and let's have a little bit of fun. All right, let's get at it.
Now, the most obvious thing is this is going to be a grouping of Of course now I got to get my phone to stop beeping at me.
This is going to be a grouping of the 1 2 4 8s cuz we obviously can't ever put a 3 6 anywhere on here and we can start to pair away at where the 1s and the 8s can go. Can't put a 1 or an 8 in any of these positions cuz you'll have multiple digits looking at each other. I have to be that.
Now, that tells us there's twos and fours looking at all these. So, we have this interesting little pattern going here.
Now, question's going to be what does that do for us? We're probably going to have some restrictions on some of these.
We're going to have a restriction here cuz we can't do 1 2 4 8s. This will be a 3 6 pair and that [clears throat] might actually be a beneficial to how this will work.
I don't think we have anything on these other ones just yet cuz the restrictions aren't great.
So, let's start looking at you and seeing what our options are for when we start going down this line from where the starting points can be.
So, can't do 1 2 4 8s. We have 3 5s 7s and 9s or 6s too, excuse me.
Yeah, just make sure the brain ain't function properly so I got to make sure I'm doing this right.
>> [clears throat] >> And do do that looks all good. Okay. So, let's start digging into what these can actually be. Can this ever be a 3? The answer is no cuz you'd have to put a 2 or 4 here. Can't do it.
Can it be a 5? Can't go down to the 4 so it'd have to be 5 6 7 8 9 which it could be.
Could you be the 6? It wouldn't go down to the 5 4 so it'd have to go up 6 7 8 9s. Not going to work.
The 7 would have to go down 7 6 5 4. Not going to work.
9 8 7 6 5 is not going to work cuz the 3 6 is staring at us. This is just a 5.
And we said because we can't [clears throat] go down to the 4 this has to go up to the 6, the 7, the 8, and the 9. And that should set this all off.
Cuz you will be 1 2 4 8 4 2 1 2 2 4 8 4 2 and 1.
Good. Now, [clears throat] these have to be a 3 5. Let's put them in. Don't think it tells us anything really at the moment, but we'll put them in anyway.
We probably have to get into one of these other strings or bands of crop keys to move on. Let's look at you for a second first.
>> [snorts] >> You can't have a six on you so you can't be from three six. You can't have a four on you so you can't be from the four eight or the two four. You have to be a one two pair. So you will be the two, you will be the one.
This can't have a one or a two on it, but it could be four three six or eight.
Again, I don't know if that's too helpful. What about these three digits cuz they're just givens, not given as in we know what they are, but they're just given options three eight nine.
Yeah.
What about these cuz these are similar, but we have a crop key here that might start to parse out what it can and can't be.
One [snorts] two and five. You can't be a two and you can't be a one cuz we can't put a two over here.
>> [clears throat] >> What about the options being a two and the five what's staring down the here?
So if that's a two, this can't be a one so it would have to be a three, which it can be. If it's a five, it can't go down to a four, it have to go up to a six.
Give us a three six pair.
I don't know if that tells me anything though.
One of these two has to be an eight I just noticed.
But I don't think we can rule this out.
>> [clears throat] >> We might need to go over to here or here. Which one is better?
Let's go here first cuz we have a lot of restrictions along this line.
So you can't put a one here, can't put a two here. We can't put a three here either cuz we'd have to put a two or a four. That's not going to work. Can't be a four so five is the starting point.
Can't go down so it have to be five six seven eight nine, which I think works.
Uh we can't put a six cuz it wouldn't be able to do 6 7 8 9 or 6 5 4.
We try to put a seven, it would be 7 6 5 4, not going to work.
Can't do 7 8 9.
Can't put an eight. What about the nine?
9 8 7 6 5, I think that works. 9 8 7 6 This is just a seven no matter what.
>> [snorts and clears throat] >> What are these three? Cuz they're going to be beefing three, five, and nine.
There will be a three here. So, you can't be a three, so you can't be a six.
Okay?
Gave us some pairings there, but I don't think it did enough. Let's go down here.
Let's start with this and do the [snorts] same kind of uh grouping and thought process that we did the other ones.
Can't put a one in here, so we could looking at two, three, four, sixes, and eights.
Can you be two, three, four, six, or eight?
The two is going to be right out cuz two, three, four, five, that'd be twos and fives looking you.
Three can't go two once, it'd be three, four, five, six, that'd be a 3 6 pair.
No.
>> [snorts] >> 4 3 2 1 I think Oh, no, it can't work cuz of the two and the one here. I was going to say by this it could, so if no on that. 4 5 6 7 could actually work cuz this could be a 2 3.
6 5 4 3 will not work cuz that would break this. 6 7 8 9 I think could work.
And then eight would have to be 7 6 and five, and that could work as well.
Cuz this again could be a 2 3.
Now, was this always a 2 3 maybe?
Cuz we know the four says this is a 2-3.
4 5 6 7 So, you'd have to be the two. The six would have to go up to the seven. But, if I could put a six here, you are the three, you are the two. The eight seven six five says you are the two You're always the 2-3. Doesn't matter what option it is. You will be six, you will be three, you will not be a two.
Okay.
What does that tell us?
Do we go to you now?
Cuz I think we had given options here.
You can't be a six or Well, no, actually, you could be an eight. Okay.
4 5 6 7 6 7 8 9 8 7 6 So, we always have sixes and sevens on here.
It seems like.
So, [snorts] what does that make you?
You can't be 1 2 3.
I guess you could be a four Well, you can't be a four or five cuz of the four or five pair staring at this down.
>> [snorts] >> So, we can't put a four on this.
We can't put a five.
Yeah, cuz you won't be able to go to the six cuz we know there's a six. We We just said we can't put a four or five.
Can't have a six, can't have a seven. It has to be an 8-9, and you have to be the eight and the nine. This is the only way it works. Okay.
Oop.
Again, computer's trying to screw me here. This eight says you are a six, which means you are the four, five, and seven.
You can't be four or three, but I think you can still be two or eight. What are You are just a given one.
Okay.
Did any of these tell us anything going up here? I don't believe so.
What are these three digits though?
Three, five, and six. That will tell us what this is though. You will be our 1-5.
Now, we start [clears throat] plugging stuff in here for Or do we go over here?
I'm not quite sure. Let's go still over here. We have some options here. So 4 5 7 and 9 you will never have a four on you. You will never have a five on you.
You will never be a four. So you are a given four.
And 3 5 6 as you can't be a can't be a five.
Thank you. So this one is the given five as well. Okay. Now what does that tell us about these?
Need ones, sixes, sevens and nines. You can't be a one.
You two can't be sevens.
I don't know that we have anything there just yet. This is a 6 7 9 1 6 Oh wait.
There has to be all right. It's like this six here. These can't be sixes.
Okay.
Uh what did that do for us?
I don't know.
So maybe we cut across over here. Maybe this crop key here will tell us something.
What are these? 3 7s and 9s?
If you're a nine, you'd be an eight.
That'd be a 6 5 9. I think that would work.
If you're a seven you could be an eight.
You couldn't be a six though. So I try to put a six here with the seven. This becomes an eight nine and this is busted.
So the nine and the seven both say eight. The three though could say two.
>> [clears throat] >> Cuz it can't go up to a four.
Is there still anything over there? 1 6 5 8. I guess we know one of these two is a two.
Is there Sudoku maybe we should be looking at?
You can't be a one.
So one of these two is One of those two will be Okay.
Let's try something else.
Twos. Okay, there's a given two sitting here.
Are twos just going now going to be done?
>> [clears throat] >> No, we have an X-wing left on twos.
Okay.
Uh let's try the Let's go keep going up this line and see if we can just work through these.
I don't really see anything on three.
Four fours, one of those two will be a four.
One of those two will be a four.
Nah, not really.
You can't be a five.
Uh what about the What are these three maybe? Three, six, and seven.
We know one of those two will be a seven. I don't like that. Okay, [clears throat] let's keep going back to our Sudoku.
Don't see anything on the sixes, really.
We know one of you are the sevens.
Nope. Eights, maybe?
One of those will be an eight.
One of those two.
Eh, not really seeing a whole lot there.
Not really seeing a whole lot here, either. So, there must be one of these um crop keys is telling us something else.
What about you?
What can you be, maybe? We'll go from that. Can't have a one, can't have a two.
Can't have a three cuz we can't put two or four next to it.
Can't be four.
Could be five as long as it paired with the six, that doesn't appear to break anything.
Could be six if it pairs with the seven.
Doesn't appear to break anything. Could be a seven.
If it pairs with a six or an eight, can't be eight. Could be nine if it pairs with an eight.
>> [gasps] [sighs] >> Not the greatest thing in the world there, I don't think.
So, what else do we have? 3 5 6.
There's got to be something in here that's going to pull this thing across for us.
Unless there's maybe Oh, it can't that put number three here.
Cuz we knew there was a three.
3 4 6. I don't think we can restrict any of these other ones too much just yet.
And I don't think this grouping is super restricted either, is it?
Cuz if that was a six, that'd be a three, that'd be a seven and a five.
>> [snorts] >> I don't see a problem with that.
And the 4 8 doesn't really have any restriction whatsoever.
Okay, we're going to look up one of these um 3 5 6 8 9.
One of these rows or columns has to have something that's going to tell us one little nugget of something.
Seven, can you be a 5 6? You'd be a three.
You'd just be eight or nine.
Can you be nine?
Would you all Oh, no, one of these two is always a three, I guess if that sells me.
Cuz if this is a 5 6, you're a three. If this is the 9 8, you're a three.
Again, I don't see how that tells me much. Is there Was there something back here I missed?
9 8 [clears throat] 6 1 2. What would you be?
A 5, I guess.
5 6 You always a 1.
You are always a 1.
>> [clears throat] >> If this is a 5, this is a 6. You're a 9, you're a 1. If this is a 9, you're an 8, you're 6, you're 1.
So, you are 1.
If that's the case, you have to be 1, you have to be 4.
Okay.
There's a little something there.
You now have to be a 3 because of the row.
Stop double-clicking, computer.
5 9 and 6 8, okay.
6 7s 8s and 9s. Okay, so we know one of these two is going to be a 9 now because of the row, so you can't be You are the 6.
If you are the 6, that's going to set these all off. So, you now have to be the 8, the 9, the 2, the 5, the 6, and then this will be the 5 and the 9.
You can't be 5 or 9.
You can't be 7.
So, you can't be a 6. This has to be a 7 8. It's the only thing that work Well, no, it could be 7 6, excuse me, but you have to be a 7.
>> [snorts] >> And you two We've got to tell me whatever this is, right? Yeah, this has to be the 6 cuz we can't put the 6 there. That's what it was. 8 This is a given 6. You are the 3 we need. So, we probably now have some Sudoku we can dive into.
Yeah, cuz this is the final one.
This is the final two.
The 3s are not quite as copacetic.
Fours are still an X-Wing, but you can't be a four anymore, so you can't be an eight.
Actually, the three just tells you what this crap gives. You are the eight, so you are the four.
That's going to be a five-six pair.
Okay. Uh these are not eights. We're done with eights. We will be once we put it here.
All right, let's go to these two.
We need a five and a seven, so you will be our seven and our five, which means this is a three-nine, so you will be our seven-nine, seven-nine.
You are five or six. Now they put the five here, this has to be the six and the five.
That'll get rid of the sixes here, so that's the three-seven. You will be the six and the three.
You can't be a three or a nine, so you are the eight. You're a given whatchamacallit, nine.
>> [clears throat] >> Okay.
What are What's the final? Cuz this is a given. It is six.
And then these two are four, which goes here and seven, which goes here. Now it's going to break these open, three, seven, five, three.
And the two will tell us the final of it, three-nine, nine and three. There we go. Okay, cool.
It's all posted correctly. 18 minutes, not bad at all, 500. So quite a few solves.
>> [cough] >> Excuse me.
In a couple of days there, but like I said, it wasn't supposed to be too difficult. The This was kind of a fun little thing to get into. Now this was not difficult to see what was going on here at the start, >> [snorts] >> but then you just kind of had to go through some of the options to see what could and couldn't work, and then there were very limited options of it, so really enjoyed it, and again, not feeling the greatest in the world.
Like the nicer, easier puzzle here. So, I hope you all did as well. With that said, I'm going to take some cough medicine.
>> [laughter] >> And we'll see you in the next video.
Thanks a lot.
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