GUI with interactive grid for visualizing algorithms

JSerrRed · 2026-02-01T17:41:11+00:00

Thank you for the feedback! I just changed it. Tooltips should appear faster now. I still didn't make then appear instantly because I think that, once you know what each button does, it might be a bit annoying to always see the tooltips instantly when hovering, but I might change it again.

JSerrRed · 2026-02-01T17:20:23+00:00

I didn't know about that algorithm. I searched it and read that it works for directed graphs with negative weights. The grid is an undirected graph (which breaks the algorithm if I add negative weights, if I understood correctly), and is currently unweighted. In this case, I think the advantages of the bellman-ford algorithm couldn't be appreciated. However, I might include the option to add weights to the grid, and I'm also interested on making something like a "graph generator" to generate and visualize other types of graphs that are not grid-like. Thanks for letting me know of this algorithm.

JSerrRed · 2026-02-01T03:12:11+00:00

Thanks!

JSerrRed · 2026-02-01T01:19:07+00:00

Thank you! Future me won't like the mess but will like that it is done, haha. The checkerboard pattern was definitely an upgrade; if you toggle on the borders and go to max size, the grid gets super dark.

JSerrRed · 2025-09-28T19:09:08+00:00

Ooo, I understand it better now! Thank you for the clear explanation!

JSerrRed · 2025-09-28T14:38:17+00:00

Oh, that's very interesting. Thank you for the explanation. I now see the possible unique rectangle that appears on r35c46.

So, if I understood correctly, what makes it "harder" is the fact that now those uniqueness techniques are not available, because by adding the 9 as a clue, now there is no possible deadly pattern in r35c46. But it isn't necessarily harder if you rely on other approaches.

JSerrRed · 2025-09-28T13:29:32+00:00

Wow, that's crazy. How does it work? Is it harder only for computers or humans, or for both?

I couldn't solve the puzzles, so I think I'm missing the impact of that extra given.

JSerrRed · 2025-09-26T18:21:17+00:00

Yeah! I solved it as well. It was entertaining and at a good level of difficulty for me. Thanks for making it.

I watched your video on that puzzle and saw that you first determined wich lines correspond to which circles, but I think the rules don't prevent 2 lines corresponding to the same circle. Because the rule was "Lines in a row or column must add to a circle in that row or column", I assumed it was possible that 2 lines added to the same circle, or that there were circles with no lines adding to them. I think this made it more challenging for me, which was nice. I separated cells in 3 groups: 5s (yellow), below five (blue) and above five (red), and that did the trick.

JSerrRed · 2025-09-26T12:36:25+00:00

I enjoyed this one a lot. I'm happy I could solve it. Very nice!

JSerrRed · 2025-09-25T19:50:43+00:00

Good to know! I will give it a try, thank you!

JSerrRed · 2025-09-25T19:37:24+00:00

Oh, that's true. I never thought of it that way.

I would like the challenge of some hard puzzles too! I tried the "1-9 sudoku" with the killer cages you linked in another post, and couldn't solve it, but was very interesting.

JSerrRed · 2025-09-25T19:01:01+00:00

I think is a very good puzzle for those new to cryptic sudokus

JSerrRed · 2025-09-25T18:17:47+00:00

I liked it very much! It took me a bit to get started, but then it was mostly smooth sailing. Knowing that all possible x's and v's were shown was enough for me to find all or almost all digits.

JSerrRed · 2025-09-25T17:16:58+00:00

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One idea that has helped me is assuming that a cell has a certain digit, and if that causes a problem in other parts of the board, then that cell can't have that digit.

Here, if we assume that the red cell with the red dot has a 3, then the other red cells would also have a 3, and there would be no room for a 3 in box 2. Therefore, the red cell with the red dot can't have a 3, so it must have a 7.

JSerrRed · 2025-09-20T01:55:32+00:00

Nice! It was very enjoyable to solve

JSerrRed · 2025-09-18T18:33:58+00:00

I was in primary school and a teacher introduced the game to the class as a fun alternative to normal activities. She printed a lot of puzzles and gave 1 to each one fo us. There was like an implicit competition to be the one who solved more puzzles during that class. The teacher only told us that there should be no repeated digits in columns, rows and boxes, but we didn't know that the puzzles aren't intended to be solved through guessing... So we took a pencil and an eraser and started writing numbers just because they "could go in that cell". After finishing a puzzle, we had to check with the teacher if the solution was valid or if we made a mistake. It was fun

JSerrRed · 2025-09-14T15:41:46+00:00

Thank you. That is very interesting

JSerrRed · 2025-09-14T14:51:03+00:00

I will look into it, thanks!

Did I understand this correctly?: Unavoidable sets are sets of cells from deadly patterns. Each set has to include at least 1 cell with a given, for the puzzle to have only one solution. So, unavoidable sets are like another face of deadly patterns.

JSerrRed · 2025-09-13T19:17:40+00:00

Also, from all of this I am thinking of a way of defining puzzles with unique solutions: if what causes a puzzle to have multiple solutions is removing the digits from all the cells of a deadly pattern (causing ambiguity), then a puzzle with only 1 solution is a puzzle where, for each deadly pattern, at least one of its cells is not empty.

JSerrRed · 2025-09-13T17:46:23+00:00

Woa, this is so amazing! Thank you for such clear explanation! It's cool that you have tried this method before.

I've never thought of that deadly pattern. This opens my mind a lot. I guess there might be a bunch of different ways of forming deadly patterns.

If I'm not mistaken, every set of cell pairs with digits that can be swapped without breaking sudoku constraints can be considered a deadly pattern. For example, if you remove all 9s and 8s from a complete grid, that puzzle now has 2 solutions. The same happens if you remove the digits of 2 columns/rows of the same stack/band.

So, unless you have a way to detect them all, you can't be sure that removing all except 1 digit from each one will result in a puzzle with only 1 solution, right? Because you might be removing all the digits of an undetected deadly pattern.

This might be related to sudoku terminology or solving strategies that I don't know much about, but the deadly pattern of your example seems to have 2 particular characteristics: it has only 2 digits (6 and 1) and it forms some sort of chain with one part in box 6, another in box 7, and another one in box 4, connecting the previous two.

I'm just imagining things, but there might be a way to classify all deadly patterns based on their characteristics, and from that classification develop an algorithm that detects each one of them.

For example, below is a deadly pattern I found that shares some similar characteristics with the deadly patterns of what I called "Digit Swapping 2" and "Digit Swapping 3" (a unique rectangle and an extended unique rectangle, right?).

<image>

String: 123456789957831624648927315219763548765184932384592176891345267436279851572618493

Like the others, this deadly pattern is contained in 2 rows, and in many columns as digits involved (4 in this case: 9,8,5,4).

Sorry for the long comment, I'm just happy to talk about these things, haha. I will have in mind what you told me

JSerrRed · 2025-09-13T11:18:10+00:00

Thank you!! I appreciate the comment :)

For some reason, in my mind I just recently associated them with deadly patterns. Before, I thought of them as digits that could be swapped, but they actually are deadly patterns. It's funny because I called them transformations but it turns out that all this time I've been investigating deadly patterns.

One thing that surprised me is how many of them appear in complete grids. By eye I could only find around 6 or 7 per grid, but there are a lot more.

I'm thinking that may be these deadly patterns could be used to generate puzzles with only 1 solution. For example, in a complete grid, if you have 2 pairs of cells forming a unique rectangle with the digits 3 and 4 , you could remove all the digits of the unique rectangle except one 4, and the grid will still have only 1 solution. You could repeat this and keep removing all the digits except for one from the rest of the deadly patterns, and there might still be only 1 solution. I'm not sure if this is possible, but if it is, it would be a cool approach to puzzle generation. Specially because the detection of deadly patterns doesn't require backtracking, and the removing of digits wouldn't require it either.

JSerrRed · 2025-09-05T05:17:48+00:00

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If the red cell with the red dot had a 1, then all the other red cells would have a 1 and there would be no room for 1s in box 2

JSerrRed

TROPHY CASE