Sudoku U Papers: Nemateleotris Helfrichi

Added: 2026-05-22

[00:00:15]Hi, welcome to Primester Puzzles and welcome back to Sudoku U, which is a series of puzzles created by students from um university or normally university classes where puzzles are used as part of the course material.

[00:00:30]Um and today I'm doing a puzzle called Nimm ein Teil deines Selfrischi by um Della Sieca. Um and apparently this is some sort of fish. I know nothing about this and I was going to say, "You know what? I'm just going to solve the puzzle because I am not an expert on this. I'm barely an expert on puzzles." Um but you can definitely look this one up yourself if you're interested. There'll be a link below to where you can try the puzzle for yourself as well as to the entire um Sudoku U and Sudoku U2 playlists where you can find all of the puzzles in this series. But let's just get straight on with the puzzle cuz this one looks interesting. Um and I'm running to a time constraint. So, what do we have? We've got normal Sudoku rules. So, that means in every box, in every row, and in every column, the digits 1 to 9 must be placed without repetition. We have Renban lines, which is digits along one of these pink Renban lines must form a set of non-repeating consecutive digits in any order. So, if we use this short line for an example, if I was to make this a one, then the other digits on the line would have to be two, three, and four because 1 2 3 4 is a run of four consecutive digits. If for example I made this a five, then 2 3 4 5 would be valid, 3 4 5 6 would be valid. I couldn't do 5 7 8 9. That wouldn't work not just because of the Sudoku because 5 7 8 9 is not a run of consecutive digits. If I was to make 5 6 7 8 however, that is a run of consecutive digits cuz if I took the numbers off and sorted them, they would be a run of digits. That's how Renban lines work.

[00:02:04]And then we've got arrows. Digits along an arrow must sum to the number indicated in the circle from which the arrow emerges. Okay, digits may repeat along arrows. So, the sum of those three digits goes there. The sum of those three digits goes there. They're the rules of the puzzle. I'm going to restart the puzzle to restart my timer.

[00:02:22]Let's give this a shot. Okay, so let's start with the standing arrow thing, which is the minimum I could put into those is 1 2 3 because no repeating in those digits cuz they're all in the same box. 1 + 2 + 3 is 6, so this has to be at least a 6.

[00:02:37]Um Ah, no, I've got better. The minimum those could be is 1 + 2 + 3 and the minimum those could be is 1 + 2 and 6 + 3 is 9. So, those are forced to be the absolute minimums. So, 1 and 2 are absolutely in those or can't be in those cells. So, 1 and 2 can't be in those cells, but I need to put 1 and 2 in this row. So, those are a 1 2 pair.

[00:03:02]Which means the minimum I could put here is 3 and 4.

[00:03:06]And there must be a 3 here because if there's no 3 in those two cells, the minimum this could be would be 4 5 and 4 5 + 1 would mean that would need to be a 10 and I can't put a 10 into a single cell. So, there must be a 3 in here.

[00:03:19]Now, [snorts] if it's 3 4, I could go with 1 2. This must be 3 4 5 and that can't be a 5 and that one can't be a 4 because of Sudoku. But, um there must be a 3 in here because if it's 3 4, I could go with 1 to get to 8 or 2 to get to 9 and if it's 3 5, it must be a 1 to get to to 8, but this must be an 8 or a 9.

[00:03:41]And it can't be a 9. If this is a 9, um this Renban line would be forced to be 9 8 7 6 cuz I can't go up from 9. There is nothing higher than 9 in Sudoku digits.

[00:03:52]So, if this is a nine, these would have to be 8 7 6, but I can't put eight in this line. So, that has to be an eight, which means I can't make this 1 3 5.

[00:04:00]There's no five on this line because the minimum with a with a five would be 5 3 1 cuz I can't do one and two on the line. So, I can't put a five on the line. This is 3 4, which is seven and a one with a two. That's beautiful. I love that.

[00:04:16]Now, there must be a seven and a six on this line.

[00:04:19]Well, actually five is in one of those two.

[00:04:25]It feels like it is here because I can go up from the eight, but if I go up from the eight, this is 9 >> [snorts] >> And if I go down, it's 7 6 5.

[00:04:37]So, six and seven are definitely on here. This is a five or a nine.

[00:04:44]If this is a five, this is 6 7 8. Oh, wow.

[00:04:49]That's insane. If this is a five, I can't go down because if this is a five, I couldn't go down to four. So, there'd be no four on this line, so I'd have to go up from five and this would be 5 6 7 8. But this is if this is a nine, I can't go up. I have to go down and this would be 8 7 6.

[00:05:06]So, this is always 6 7 8 and there's no eight there and that's an eight. I don't think I've seen that trick before.

[00:05:12]But it's very cool. That puts eight in one of those two.

[00:05:16]1 2 3 4 5 6 7 8. These are five and nine.

[00:05:21]And that's a five nine pair, meaning that's not a five. So, in the box, that's the five. That's the nine.

[00:05:27]That's the five, which means this is 6 7 9. That's very cool.

[00:05:35]And this is 6 7 9 for the row with that digit being the same as that digit. That's not a nine. That's not a nine because now nine has to be in one of those two.

[00:05:45]That's very cool. The two looks down saying there's no two here. There's no nine or eight here.

[00:05:53]But nine has to be in one of those three by Sudoku, but not in the arrow. Nine is in one of those two.

[00:06:00]I can't put nine on an arrow. If I put nine on an arrow, it'd be nine plus two other digits to go to a single digit, doesn't work. That's the nine. So, we know now these are eight eight, seven, and six.

[00:06:16]Nine and nine now puts nine in one of those three.

[00:06:22]I'm not Well, it can't be on an arrow for the same reason. So, it's in one of those two. Nine here would make this eight, seven, six, five, four, and I'm not sure why that's not possible yet.

[00:06:33]I mean, it's possible it's not possible.

[00:06:35]You can measure or measure and be damned, but I'm not sure why not yet.

[00:06:42]Eight and eight puts eight up here.

[00:06:47]Mhm.

[00:06:50]Minimum here is two, three.

[00:06:53]Minimum here is two. That's interesting, isn't it?

[00:06:57]Cuz I can't put a one in either of those. So, the minimum here is two plus three, which is a five, and the minimum here can't be one to Oh, it's three.

[00:07:05]So, the minimum here is five, the minimum here is three cuz it can't be one or two. Five plus three is eight.

[00:07:10]This is eight or nine.

[00:07:15]So, that can't be a nine, could it? Oh, that'd make that a nine and one of those two a nine.

[00:07:21]Maybe.

[00:07:26]But [snorts] I can't Yes, I can't not put a two on this. If I don't put a two on this, the minimum would be three, four, which is seven, and the minimum here is three, and seven plus three is 10, and I can't put a 10 there. So, that's if I don't put a two on this. So, I must put a two in one of those two, and that two says it's not there, that's the two.

[00:07:47]Now, those two digits sum to six or seven.

[00:07:54]Minimum here is three.

[00:07:57]I could go three three.

[00:08:00]I can't put a five in either of those.

[00:08:01]These are all three four, aren't they?

[00:08:04]If I put a five in one of them, if I put a five here, five and two would be seven, and that would need to be No, no more than two. If I put a five here, five two, that would need to be no more than two, but it can't be. These are all three and four, and the four looks up making that a three. So, this is five, this is three or four to get to eight or nine.

[00:08:24]This is now at least a four.

[00:08:27]So, if that's at least a four, and these are at least one two, this is at least a seven cuz four plus three, and there must be a one in here because if there's not, it'd be four plus two three, and that would need to be This would need to be nine. Four plus two three is is is nine, and that can't be a nine. That's a maximum of seven or eight. So, there must be a one in one of those two, and it can't be higher than four. So, this is from one two three because it [snorts] can't be higher than four, and even if this is one two with three, this can't be higher than five.

[00:08:59]So, this is four or five.

[00:09:03]There's no two on this line. So, there's no one on this line because if I put a one on this line, it would have to go one two three four five six, but I can't put a two anywhere on this line. There's no two in those, and there's no two in those. So, there's no one on this line.

[00:09:17]>> [snorts] >> So, I can't put one in any of those.

[00:09:19]Those are filled, and I can't put one in any of those. That's a one.

[00:09:22]Putting one on this line now by Sudoku because these two ones say there's no one in any of those, and that one says not there. There's a one in one of those two. So, this line is now one two three four five six. There's no eight on it.

[00:09:36]There must be a two this line. And it can't go in any of those or there.

[00:09:42]So, that's the two, that's the one.

[00:09:47]That's very cool.

[00:09:49]And these, I'm going to mark the quadruple a 3 4 5 6. There's no three there.

[00:09:56]There's no four or five there. That's a three or a six.

[00:10:07]Where's nine in this column now? I can't put it on this line.

[00:10:11]This nine says it's not in the box and that can't be a nine because of that.

[00:10:14]That's the nine, this is a 6 7.

[00:10:21]Okay.

[00:10:27]One is in one of those three.

[00:10:31]But [snorts] I don't think that's the way to look at this.

[00:10:36]>> [snorts] >> There must be a one.

[00:10:38]But no, this is the way to look at it.

[00:10:40]This is a six or a seven. So, there must be a one on this arrow. This is either 1 2 3 or 1 2 4. But the one has to be in one of those two digits. Because if I don't put a one on this, the minimum is 2 3 4 and that would need to be nine, which it can't be. So, there must be a one. And it can't be here. So, there's a one in one of those two saying that's not the one, that's the one. But there must be a two on this as well. Because if I don't, the minimum is 1 3 4 and that would need to be eight. So, there's a two on this arrow in one of those two.

[00:11:08]Because it can't be there.

[00:11:15]Can I take that any further? Well, these two ones are looking down saying no one in those. So, this is 3 2 1.

[00:11:24]Three and three puts three in one of those. Two and two puts two in one of those. So, two and three are both in those.

[00:11:32]That's a 6-7 pair, wasn't didn't see that. 1 2 3 4 5 6 7 5 8. These are 5 and 8.

[00:11:49]That can't be 6 7 or 8.

[00:11:52]That Neither of those can be 6 7 or 8 because they see all of those. That digit can't appear in any of those three cells cuz it sees it in those see them in that one in the column and see those in the box. So, this can't be 1 2. It could be 3 4 5. Can't be 6 7 8. Could be 9.

[00:12:17]Didn't do as much as I thought it might.

[00:12:26]The one is looking across making that the two and that the one. Two is looking up saying that's not the two, that's the two. Looking across saying that's not the two.

[00:12:43]Something with the Renban lines.

[00:12:48]It probably is.

[00:12:50]Like I haven't looked at this one at all.

[00:12:57]Like there's no eight on this line.

[00:12:59]Because this eight can't appear on it.

[00:13:02]But, it's 1 2 3 4 5 6 digits long and it can't have an eight on it. So, it's 1 through 6 or 2 through 7.

[00:13:20]So, where's the one? Oh, no, I don't need a one on this line.

[00:13:24]If there's a one, it's there.

[00:13:28]It must have a two.

[00:13:33]Two in this box is in one of those two.

[00:13:35]It must have a two in one of those two.

[00:13:41]If that's the two, that's a three.

[00:13:46]And then that would be a three.

[00:13:49]Uh hang on a minute. That's a two-three pair.

[00:13:58]That's a really weird two-three pair.

[00:14:01]Because I have to put two and three on this line. Because I can't go as high as eight. So, it's 1 2 3 4 5 1 2 3 4 5 6 or 2 3 4 5 6 7. Two and three must be on this line.

[00:14:13]Now, because two can only go in those, if that's the two, that's the three.

[00:14:21]So, if two is here, Actually, I'm not sure about that, actually.

[00:14:31]If two is here, two is here.

[00:14:34]And then I don't know that has to be three, because I could put three over here. I could put three there, maybe.

[00:14:41]Yeah, okay. No, I almost made a mistake.

[00:14:45]Oh, no no no no no. This one is looking across saying there's no one there. So, there is no one on this line.

[00:14:51]I can't put one in any of those, and I can't put one in any of those. This is 2 through 7. 2 3 4 5 6 7 is what this is.

[00:15:00]There's no two there. There's no three there.

[00:15:03]There's no two or three in either of those.

[00:15:09]Why is there no three there? There's definitely no two in either of those.

[00:15:16]There could be a three there.

[00:15:18]If there's a three there, that's a three.

[00:15:20]Which seems fine.

[00:15:28]That is a 678 triple. I know what this triple is. 3 4 9 There's no 9 there.

[00:15:36]So, that's a 3 4 pair.

[00:15:40]So, in that column 1 2 3 4 5 1 6 7 8. These are all 1 6 7 8.

[00:15:52]And that one can't be a 6 7 or an 8.

[00:15:57]Yeah, what could this be? It has to be from 1 2 3 4 in order to make the 6 7 and it can't be 2 3 or 4. That's the one.

[00:16:05]Which takes one out of both of those.

[00:16:07]That's a 678 triple. And that digit must be that one.

[00:16:11]But that's a 678 triple, meaning that is a 9, which is means that is a 4 to make the 5 + 4 work.

[00:16:19]Which means this is the three and I can take the three out of both of those.

[00:16:25]The 9 looks down making that the four, that the nine.

[00:16:28]That looks up taking nine out of those, which I could have done from that. The 3 5 I'm not sure what that does yet.

[00:16:36]Okay, that digit is that digit because it has to be one of those three and it can't be either of those two.

[00:16:44]I don't think I'm doing great at this. I think I've dropped the ball somewhere, but I've been doing that a lot lately.

[00:16:50]Me and balls don't mix. 1 2 3 4 5 6 7 8 9. So, these are three and five.

[00:17:02]Which means that's a two.

[00:17:04]Because I have to put three on this line somewhere.

[00:17:08]Cuz this is 2 3 4 5 6 7 and I have to put three in there somewhere. So, because I need to put a three on this line somewhere and I need to put three in one of those two cells somewhere.

[00:17:20]That is taking up the two threes that I can put in rows five and six. If that was a three, that would be a three, and I couldn't put a three on this line, and I'd have a problem. That's a two.

[00:17:31]So, 1 2 4 or 1 2 5, but that means that's not the two, that's the two, that's not the two.

[00:17:39]Which is the least helpful deduction.

[00:17:44]This isn't a one.

[00:17:47]Oh, but this can't be a three anymore because that's a three-five pair. That's a four, that's a seven, that's an eight, meaning that's a five.

[00:17:55]That's a five by Sudoku.

[00:17:58]So, there's no seven on this line cuz I've already got the seven. There's no five in either of those two.

[00:18:06]>> [clears throat] >> So, these are three, four, and six.

[00:18:12]Five is in one of those two because I have to put a five on this line, meaning no five there, but the five that must be there makes this the three, this the five.

[00:18:21]I can get rid of this highlighting now.

[00:18:25]I think.

[00:18:28]This is very strange puzzle. I like it, though. The seven looks down making this the six and this the seven. The five looks up making this the eight, taking eight off here.

[00:18:37]There could still be a nine on this line.

[00:18:40]9 8 7 6 5 4.

[00:18:43]There must be a four on the line.

[00:18:48]1 2 3 4 5 6. This is four or six.

[00:18:55]If this is a three, that can't be a nine.

[00:18:58]So, it's either 9 8 7 6 5 4 or 8 7 6 5 4 3.

[00:19:08]So, there must be a five on the line.

[00:19:10]Yeah, it's it's it's long enough. It's 1 2 3 4 5 6 digits long. So, 4 5 and 6 must appear on the line, but I can't put the 5 in any of those. That's the 5, that's the 3.

[00:19:23]There must be a 4 on the line in one of those three, but I'm not sure which.

[00:19:34]The 3 comes out of there, but the 3 comes out of there. That's the 6 taking 6 off the line. That's a 4 5 pair making that the 3 taking 3 off here. That's a 4 5 6 triple on the line. That's the 3 taking the 3 out of there.

[00:19:54]This row? Where's one in this row? One and one means that's the one.

[00:19:59]I could have just used the one looking across. So, this is a 4 or a 6 and it's not a 4. That's the 6, that's the 4 taking 4 out of those. That's a 5 6 pair. The 6 takes 6 out of those. So, 6s in one of those two to be on this line making that the 7 taking 7 out of those two. That's a 6 8 making that the 7 looking down making that the 8 taking the 8 out of there. The 6 7 looks up making that the 8, that the 6. The 6 7 look down making that the 8. This is cool. 1 2 3 4 5 6 That's a 7 to complete the row. 1 2 3 4 5 6 7 8 9 That's a 4 to complete the box making that 6, which I could have got from the box, but I got there. It doesn't matter. The 4 looks up making that the 6. This is now a triple.

[00:20:42]4 7 and 9. I can't repeat 7 on the line.

[00:20:47]So, that's a 4 9, which means it's 4 5 6 7 8 9, but the 9 makes that the 4 and that the 9. This is not the 8, this is the 8. This is the 3 to complete the row. 4 and 3 sums to 7. I completely missed this arrow. That arrow may have helped me earlier. The 4 looks across to make that the 5 and that the four. I've had fun. Does it matter if I didn't do it the most efficient way if I've had fun? I think think the answer to that question is no. Five looks down making that the six and that the five. The six looks down making that the seven and that the six. The six looks across making that the seven and that the six and that is the solution. And it's linked to the Wikipedia article in the solution, which I'm not sure you can actually select. No, you can't. But um yeah, you can I I actually just grabbed the title of the puzzle and looked that up. I really enjoyed that one. That was a lot of fun. Um yeah, good stuff. Good good stuff.

[00:21:43]Um fun puzzle.

[00:21:45]Thank you everyone for watching. I hope you enjoyed this one as much as I did.

[00:21:49]There was some really cool deductions in that one. Um and as always, thank you to Sudoku you and good luck with your solving.

[00:21:57]>> [music] [music]