In Odd Sudoku, a variant of traditional Sudoku, numbers placed in cells with shaded circles must be odd (1, 3, 5, 7, 9), while standard Sudoku rules still apply: each digit 1-9 must appear exactly once in every row, column, and 3x3 box. The solving strategy involves parity coloring—shading all cells that must contain even numbers (2, 4, 6, 8) and odd numbers (1, 3, 5, 7, 9) based on existing numbers in rows, columns, and boxes. This allows solvers to determine which cells can only contain even or odd numbers, effectively splitting the puzzle into two separate constraint systems that can be solved independently.
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WPF Sudoku 2017 Round 3 - Odd SudokuAñadido:
Hi, and welcome to Brimstone Puzzles and back to the World Puzzle Federation 2017 round three. Um, this puzzle was created by Jakub Ondrousek from uh, the Czech Republic. Um, and there'll be a link below to where you can try this puzzle yourself as well as where you can go and grab this pack as well as every pack they've released on the World Puzzle Federation archive. Um, yeah, let's quickly go through the rules. Um, oh, before I go through the rules and try and solve the puzzle, this is one of the puzzles where I did slightly change the cosmetic presentation from what it is in the pack because these were originally done as just shaded cells. So, all of the shells shells, all of the shaded all of these cells were just shaded completely gray um, for odd, but we now use shaded circles for odd and I wanted to preserve the standard presentation that we use um, for odd as much as possible. Um, I'm not [snorts] going to change it from circles to squares when everyone expec- expects squares to be even or any of that sort of stuff. So, for some of the puzzles I will do some um, cosmetic adjustment for modernization, but I'm going to try and keep that to the very bare minimum uh, um, apart from where I think it would cause too much confusion and this is one of the puzzles where I did that. So, rules. Normal Sudoku rules which means in every box, in every row, and in every column, the digits one to nine must be placed without repetition and then numbers placed in cells with shaded circles must be odd. That's it.
I'm going to restart the puzzle to restart my timer. Let's give this a shot and I'm going to do the thing I enjoy doing in one of these. I am going to shade all of the digits by parity.
Is this a fast way of doing it? No. Is it a fun way of doing it? Absolutely.
Those I think are all the odd cells, 8 4 8 6 2 4 2 4 4 6 8 2 4 and 2 um uh are all even. I've got all of the evens in box seven, those become odd.
Um I've got all of the odds in row nine, these become even. I have all of the odds in box six, those become even. I've got all of the evens in row four, these become odd. I've got all of the odds in box five, these become even. Got all of the odds in row five, these become even.
I've got all of the odds in box four, this becomes even. I've got all of the evens in column three, this becomes odd.
I've now got five odds in box one, those become even. I have Where else can I continue? I'd like to continue, please.
I'd like to fully color the grid, but it may not be possible.
Cuz if I could fully color the grid, then I could do it as two separate puzzles.
But that may not be possible.
Uh yeah, it's not jumping out at me, so let's just move on to the puzzle. So 2 4, this is even, therefore it must be six, so these have to be two and four.
The four is looking across making that the two and that the four. 2 4 6, this is eight, which means these are two and six with the two making this the six and this the two. These are the four and the six in the box with the six looking up making that the four and that the six.
Uh these for the row have to be two and four with the four looking down making that the two and that the four. Um I Right, 2 4 6, this has to be odd because it can't be 2 4 6 or 8, so this is odd.
Uh still need one more odd in the box, but 2 4 Well, where can't I put eight?
Actually, nowhere. Okay, so let's not worry about that one. Ah, but this 2 4 6, this can't be eight, so that's odd.
That's all five odds in the column now, so this becomes even.
So this is uh two because it sees four, six, and eight, that's a two. Two, four, six, eight is in one of those two.
Not what I was hoping to do, but there you go. Eight is in one of those two.
Six is in one of those two, because I have to put six in this row somewhere, and by those, it's over here.
Um, okay. Uh, no. Okay, let's see if I can finish more even Sudoku.
I may not be able to.
Oh, eight in this box. The eight can't be any of those, so that's the eight.
These now become two and six.
Maybe I need to jump to e-odd Sudoku.
Yeah, I can see stuff with odd Sudoku, so let's do it. One can't be in any of those, so one is in one of those two.
Um, and now one has to be in one of those three, so that's one, which is odd. That's all five odds in the column, so this now becomes even, which is two or six, and the six means this is the two, this is the six, this is the two.
There's got to be an eight in one of those, don't know.
Um, uh, eight is in one of those two.
And four is in one of those two, because of the four's looking in the box, but that four looks up saying not there.
This is the four, which is even. This can't be two, four, six, or eight, so this is odd odd now. That's all five odds, so this becomes even, and it can't be two, four, or eight, so this is the six. Looking down saying this isn't the six, this is the six, which is even.
Uh, >> [sighs] >> So, eight is in one of those two, and I can't see how to solve that dilemma, which is a bit of a shame.
But, it's okay.
Now, we move on to the odd part of the puzzle.
I think. I hope.
I hope. [snorts] I hope.
Um, so one can't be in any of those.
That's a nine. One is in one of those two looking up saying that's not the one, that's the one.
Seven can't be in any of those and the rest are filled, so that's the seven making this a three five. So this now has to be the nine to complete the row.
This now has to be three or nine to because it's odd that sees all it's it's an odd that sees one seven five and nine, so that's actually a three. This is an odd that sees one three and nine and five, so this is a seven.
So this sees one five and seven, so this is three or nine only and this is three or nine only.
Seven has to be in one of those two because of the seven looking up and the seven looking down, but the seven looking across saying that's not the seven, that's the seven.
Seven and seven now put seven in one of those two, but that seven says not there. That's the seven. So this is actually one three five. The one and the five look across making that the three.
Take the three out of those. This is one five with the five making that the one and that the five. This is the nine that's missing from the column. These are three five and seven to complete the box. The seven says no seven there. The three's says no three there, so three is in one of those two, so three is in one of those two.
Okay, so one three five, these have to be seven nine with the nine making that the seven and that the nine.
These one three five seven These are three and nine with the three looking across making this the nine and this the three. This row is missing its one. So this is three or nine to complete the box with the nine looking across making that the three and that the nine looking down making that the three. That is not the three. To complete this row with odd digits, those are one and five. The five is looking down making that the one and that the five.
This digit can't be one three five seven or nine. That is even. That's all of the evens, so that has to be eight. This is not eight. Makes this Well, we can do the coloring. This is odd. This can't be eight, so this is eight and therefore even. That looks up saying this isn't eight. This is eight and therefore even.
This one looks up saying this can't be eight, so this is eight and therefore even. So, these are all odd. I have done the even half of the puzzle, and now I just need to finish the odd half of the puzzle. This becomes the nine. These are five and nine. The nine looks across making that the five and that the nine.
These are one and seven. The one looks across making that the seven and that the one. The seven looks back making that the five. Take the five out of those making that the three and that the seven. The three looks up making that the five, that the three, and this is the five that hasn't been placed.
>> [snorts] >> Cool puzzle.
I like parity puzzles.
There will be something happening regarding parity puzzles on the channel this year, I really hope.
Um but, there's still a lot of planning to go on that one. So, um yeah, I don't want to say too much just yet. But, there should be something happening, I really hope.
Really fun puzzle.
Thank you to Jakub Ondroušek um from the Czech Republic for this one. Hope you enjoyed it. Um the nine-year-old puzzle, but still really good. Thanks everyone for watching, and as always, good luck with your solving.
>> [music]
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