Create Sudoku Solver with Python in 20 minutes 

Thanks a lot for the kind words, it means a lot to me!

I am glad it was helpful!

Thanks for the comment! We all get better over time if we put the hours into learning :)

I wrote more than 200 lines of code to solve a Sudoku puzzle but it didn't even work

I am happy to read a comment such as this one :)

Thanks for the kind words, great you enjoyed the tutorial!

I am glad it was helpful!

I thought that it rounds to negative infinity. If you had negative number result from // it would go to negative infinity I think.

@@Dylan-zx6ji interesting. I just did some negatives and it does round on them. Good to know.

Glad to hear that!

The return statement at the bottom of the loop "range(1,10)" makes it go back

Basically, it continues looping assuming the correct solution that was found was incorrect. So the correct solution is ignored and it moves on :)

@@Pythonenthusiast Thank you so much!! :D

it just resets the cell back to 0, go back to the previous cell and solve with the next number in that loop. Watch the original video from Dr. Altenkirch at Computerphile not some copycats and you will understand a lot better

Hey there, below are my answers to your questions: 1. The whole point of the for loops is to continue to the next number when the solution for the current number doesn't work. Let's assume you start with the first number being 1 (first cell available, so the combination of the first row and first column). Next, you move to the next cell (row 1, column 2). The script starts again with the number 1. Well, that doesn't work as it is already there in the same row. So it continues with the number 2. Great, that number is available, then it moves forward, and so on. The moment there's no solution for a given cell with all numbers 1 to 9, it goes back and changes the number before. I hope this makes it clear. 2. There could be more than one solution for the same sudoku. The script starts with the smallest number and goes up until a solution is found. In order to find another solution, basically, the script is ignoring the found solution and continues to look for another one. Hope this makes it more clear!

The key is the empty return for impossible candidate numbers, not the for loop. This guy just copied almost verbatim from Dr. Altenkirch at Computerphile. He even copied the same unconventional y for row x for column convention from that video. What a fraud and he clearly doesn't know sh*t about this algorithm

Thanks for the kind words!

Hi there, thanks for the comment, I fully agree with it, for sure there's room for simplifying. As the tutorial is mainly for beginners, I didn't spend time to find the most optimal solution, but the one that's easiest to explain/understand.

Glad you liked it!

Gracias!

have you found the answer as i am stuck at same position?

the empty return acts like an else statement after all 1 to 9 are deemed impossible for a particular cell. This guy did not know how to explain because he just copied from Dr. Altenkirch's Computerphile video

Hey there, it would solve any sudoku (as long as there is a solution).

Numpy is a separate library, so my guess is that you have not installed it yet.

I had the numbers matching, but after refreshing the website, new sudoku popped and the number changed. I didn't think that changing the numbers to match would add any value as the sudoku solver would work regardless of the numbers :)

If you use range(5), the output would be 0,1,2,3,4 (output is total of 5, but starting with 0, so it goes up to 5, but doesn't include that number). In this example, the starting point should not be 0 but 1. So, the range selected it (1,10), which means, start with 1 and go all the way up to 10, but doesn't include 10. Hope this helps!

These tutorials are for beginners and I want to point out that the range starts from 0 and goes up to 9. You are absolutely right that range(9) can be used.

Hey there. In this particular case, a so-called for-loop is being used. Instead of typing row = 1, then row = 2, and so on, we create the for loop "for i in range (0,9)". What this does is, it allocates the numbers 0 up to (not including) 9 to the letter i. Later on, this letter i is what we're using as a row. The same goes for columns, as the same approach is used. Maybe you can rewatch the tutorial, I'm trying to explain that in detail as this is a crucial part of the code.

Hey there. Unfortunately, I would not be covering a solution in VBA on this channel as I would like to keep it Python-related only.

Yes, the next series that I'll work on will be related to Fundamental analysis :)

Thanks a lot!

Absolutely.

@@Pythonenthusiast can you please tell me where to change the code??

@@Pythonenthusiast hey can you please tell me, how to get only one solution as return even if there are multiple solutions??

Irregular sudoku, 5x5, so numbers would range from 1 to 25? Solving it can be done with the same code as this one, with some minor tweaks.

I wish you lots of success and I hope this video can help you out! :)

but a very much better expanation then prof. thorsten altenkirch.

Please Respond to me

@@ramakrishna-wc9sk You need to use pip install numpy. Everything that we import needs to be previously installed. If you are not sure how to install Numpy, there's plenty of information online.

@@Pythonenthusiast Traceback (most recent call last): File "C:\Users ama krishna\AppData\Local\Programs\Python\Python38-32\sudoko.py", line 39, in solve() File "C:\Users ama krishna\AppData\Local\Programs\Python\Python38-32\sudoko.py", line 34, in solve solve() File "C:\Users ama krishna\AppData\Local\Programs\Python\Python38-32\sudoko.py", line 34, in solve solve() File "C:\Users ama krishna\AppData\Local\Programs\Python\Python38-32\sudoko.py", line 34, in solve solve() [Previous line repeated 1019 more times] File "C:\Users ama krishna\AppData\Local\Programs\Python\Python38-32\sudoko.py", line 32, in solve if possible(row,column,number): File "C:\Users ama krishna\AppData\Local\Programs\Python\Python38-32\sudoko.py", line 13, in possible for i in range(0,9): RecursionError: maximum recursion depth exceeded in comparison like this coming i'm not understanding

@@Pythonenthusiast please respond to my problem

@@ramakrishna-wc9sk In the description, you can find a link to the code that I wrote. Compare it with yours and you'll figure where your problem lies. I am sorry, but I cannot spend time solving typos for everyone individually.