Live data from Hacker News

The Miracle Sudoku [video]

youtube.com

31–40 of 150 posts

Re: The Miracle Sudoku [video]

#31

The lightning speed of his observing standard rules across the board is impressive but expected after months of practice. The agility with which he picks up new rules and starts working with them is sign of a beautiful mind. This was a pleasure to watch.

Decades of practice in fact

Re: The Miracle Sudoku [video]

#32
post #13

Earlier quoted context omitted.

Wouldn't brute force be enumerating all possible combinations of numbers until you find one where all sums are correct? Your approach with backtracking sounds more fancy

It was a long time ago, but I think I randomly filled in numbers, save if numbers were already used in each row or column, then when it reached an impossible solution, it would work backwards one level, trying new numbers. If it ran out of numbers, it would go back two columns, and try a new number. I doubt it was anything fancy. At the time, it bent my mind into knots. Programming is a wonderful mind trainer.

For those who want to see how a backtracking algorithm would work. Computerphile walked through a python approach (11 lines) a few months ago: https://www.youtube.com/watch?v=G_UYXzGuqvM

Re: The Miracle Sudoku [video]

#33

25 minutes you'll be okay with never getting back.

Once you see that each row appears to be a shifted copy of the same sequence, you'll spend at least part of that time yelling at the screen, hoping he hears you.

In fact, all rows are just permutations of the numbers 1-9! Edit: ;)

Re: The Miracle Sudoku [video]

#34

The lightning speed of his observing standard rules across the board is impressive but expected after months of practice. The agility with which he picks up new rules and starts working with them is sign of a beautiful mind. This was a pleasure to watch.

Yeah, the guy is a genius at solving sudokus and makes it look easy. It is amazing how he fast can develop new "algorithms" and the explanation for the for new rules he encounters. And the way he develops/explains those algorithms

Re: The Miracle Sudoku [video]

#35

The lightning speed of his observing standard rules across the board is impressive but expected after months of practice. The agility with which he picks up new rules and starts working with them is sign of a beautiful mind. This was a pleasure to watch.

I though that too at first but actually they seem well practiced too. Eg other sudoku-style puzzles also have knight move rules. The main trick I missed is the forking one (if I put a 3 here then it reaches here and here by knight’s move therefore it can’t go here).

That said It is still impressive and I think practice is not sufficient to explain how fast he is at it.

Re: The Miracle Sudoku [video]

#36
post #25

Earlier quoted context omitted.

It's more that solving Sudoku by Brute Force is easy. But the trouble with brute force sudoku solvers is you can't use them to create sudokus solveable by humans with a unique solution. That's the fun stuff in writing a sudoku solver/generator.

Sure you can, just brute force your way to ensure there is only a single solution. You can try all combinations and count how many reached to the end and check if count == 1. Generating sudokus while all you have a sudoku solver seems an interesting challenge. Sounds like it can be done though, just a matter of creating random boards by adding one digit at a time that doesn't break rules and check if # of solutions i…

That doesn't guarantee you that you generate a Sudoku solveable without backtracking.

The human techniques are all about forward actions only, never guesses.

Re: The Miracle Sudoku [video]

#37
Ever since seeing this video I've been wondering if there's some deeper mathematical basis for this puzzle, because of the extremely regular pattern that it happens to produce.

For example, the way consecutive digits are actually in order, but separated by a single square (and looping around the edge of the board)

Re: The Miracle Sudoku [video]

#38
There is something irreplaceable about the first time you solve a difficult puzzle, especially one that you anticipate to be daunting. As a Sudoku enthusiast (though not at Simon's level) this was surprisingly vicarious to watch for what's usually a silent solitaire experience. Well done!

Re: The Miracle Sudoku [video]

#40
post #24

I almost didn’t watch that’s because who cares about someone solving a sudoku puzzle, but that was brilliant. That’s one happy solver; it was worth it just for the absolute joy he gets from it. Amazingly quick solving too. Good to watch him develop extra strategies during the process.

[deleted]
Post reply on HN