Kurotto: A Rare But Brilliant Puzzle
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- Опубликовано: 10 фев 2025
- You can try this lovely puzzle by Ashish Kumar and Thomas Snyder from www.gmpuzzles.com here:
cracking-the-c...
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Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the eleven-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.
Thank you for watching!
Simon and Mark
Super love that ending of making them all red. Great way to end it!
This is the first time I’ve seen this type of puzzle but it kinda looks like minesweeper with black squares instead of bombs
Never heard of a kurotto before, but now I feel like I could probably conquer one if I found it.
Always a joy to discover new puzzles!
Ah, Kurotto! My first ever published puzzle on GMPuzzles was one. :) Well solved overall, there is also a unique solution argument for classic Kurottos. It mostly works in puzzles with large unclued regions for speed-solving:
You should not be able to obtain even a single cell anywhere that you can then decide to shade/keep blank arbitrarily. Helps visualize necessary and efficient shadings because you cannot leave any open area too "loose" to get seemingly multiple solutions, assuming there is indeed a unique solution. For example, in this puzzle that requires some shaded blocks moving towards the center at the end.
Not sure if that's clear, I suck at explaining. Cheers!
I think this is equivalent to saying "you can't have four unshaded squares in a (1,0), (2,1), (1,2), (0,1) arrangement", or else the middle square (1,1) may be either shaded or unshaded, violating uniqueness.
@@dansp196 Well put. :) Technically, you can have four unshaded squares around a 0 clue or an empty circle (which is itself another eyebrow-raising element within uniqueness logic). However my "counter-example" is cheaty and I perfectly get what you're saying. One more way of expressing it could be that all shaded cell groups must be connected to at least one number clue in what feels to me a vague Nurikabe-like fashion.
so no green square can have 4 green neighbors. each green square has to have at least 1 black neighbor
26 minutes, I didn't expect to be able to solve it at all but once I figured out how to start I never got stuck (I never felt sure I was on the right path until it was solved either!)
That is a fun new puzzle type. Since this was posted before the pandemic lockdown, it has too few likes. Maybe more people will be browsing and run into it now, as I did.
What an awesome puzzle! Love this idea of changing it up occasionally from the classic Sudoku!
I almost solved it in 6 minutes, then noticed that I made an error in understanding the rules so that there was an impossible circle. At least I was half proud of myself
But my solution was very close to the actual one!
I did it in 8 minutes, tried an arrangement in the seven in the bottom right corner, found out wasn't working, then tried another, found out at the end it wasn't working, but I figured out why in seconds, so I fixed that, and paused the timer with a screenshot. I verified it and it turned out to be the solution!
In other words, no logic at all, but got it really fast (I got lucky somehow)
6:06 Ruling out r7c2 is right but for a different reason. It can't be shaded because the 6 above it is already fully satisfied, because it touches a black path that already must have 6 squares.
I think you need both of what you two said. That spot cannot be in because it is touching a square that is already fully satisfied by a single black path with 6 squares in it and it cannot be in that 6 square path because if it did it would be a length 6 path touching a 5.
@@twirdman2 Yes, you are quite correct. The logic depends on also ruling it out as part of the 6 for touching the 5.
39:25. I really liked this puzzle! Lovely logic involved. I'd love to try some more of them.
This videos give me a lot of joy, they’re just simple wholesome entertainment
More please. It took me a little while to get a feel for what the rules really meant so I want the opportunity to test myself on my knowledge.
Took me 16 minutes to solve, I have never met this kind of puzzle before. Thank you for introduction!
Such a great video to watch! I really, really did not have a firm grasp on the logic on this one to begin with. I just sort of "knew" that certain combos looked right (and I was mostly right about that ...) I love finding out WHY, and how I could have avoided the pair of mistakes I had to laboriously undo.
Lovely different puzzle, VERY nice solution in the end
Only puzzle from that channel that I solved faster than Simon, wow. Thanks!
For whatever reason I keep trying to count all 8 squares in the radius of the circled number. I think that ever since I discovered Conway's Game of Life that's the way my brain functions regardless of the puzzle. Great solve and it was really fun!
Interesting puzzle and solve, I’d like to see a few more.
Nice puzzle! It has a similar feel to Battleships and Nonograms
beautiful puzzle, I really should have been able to get it
Got like 95% of it, but missed your deduction at 19:55 to finish it. Darn, great puzzle though!
Great puzzle, the end of the video made me really happy ^_^
Never heard of Kurotto before, but I like it.
You can get a lot of the solution much earlier if you assume uniqueness. If you can show that a given leg could go one of two ways, and one of those ways doesn't interfere with anything but the other one might, you can conclude that the letter way DOES interfere with something else but the former is the solution.
Notable with the 3 leg off of the 3 in the lower right; after you get the four above it finished, when you see that the three can go left or up, you can show that if it goes left, there's no way that going up contradicts anything, and therefore conclude that it does go up from there.
I'm not sure if I found the process of getting the 5's in the top right excruciatingly slow because I saw it instinctively but you were taking pains to carefully prove that every step was logically required, but what should have been 'this 5 cannot get out without touching this leg, therefore this 5 DOES touch this leg' could have done so much faster with the 5 mid-top.
Neat puzzle. My time was 9 minutes although I think I would have been significantly longer if I hadn't watched you start the puzzle and give the tip about looking for large gaps between numbers
That was an amazing puzzle
Love this one
I watched the video, then went and solved it on my own and checked it, but it said i got it wrong. I went and checked it with yours and it was identical to mine. I dont know whats wrong with it. I solved it on crack the cryptic as well
18:00
Oooh yay I love this puzzle type
If we’re allowed to assume uniqueness then we can immediately know the finally solution cannot contain five unshaded squares in a cross shape. If such a thing were to occur, then you could Shade the center of the cross and get another solution.
At 16:00, I'm not sure I follow the logic about the 6 you're using. I understand that on the side of the 4, at least 1 square has to be black. But how does it block a 5 black area coming from the 7? I don't see how. It was still the right solution, but I'm not following the conclusion at all.
Thagor actually, on the side of the 4 (left/up), there must be at least two black squares. Hence at most 4 blacks on the right/down sides. Hence the 5-string can't connect to the 6.
@@lucas29476 Oh yes, you're right, there needs to be at least 1 black square next to the 6, but it will be part of at least a block of 2. Ok, thank you.
10 minutes, first time encountering this type of puzzle.
I'm half decent at doing Sudokus but for some reason, I don't get this type of puzzle - I don't have the logic to complete them somehow.
This was lovely fun, thanks! Simon, I wonder why you tend to use green for bad/excluded/stop and red for good/allowed/complete? My mind jumps to green for go/good/allowed and red for stop/no/rejected because of US traffic signals so I often mark up puzzles the opposite way. In this case I found it useful to mark incomplete regions grey, only coloring them black once I fully defined the region.
I think he does it because green is easier on the eyes than red.
I have noticed that he uses green for squares that will need a lot of that color.
So most of the puzzle will be green, and easy on the eyes, and not red and harder on the eyes.
Or he may have a reason only known to him, but I am glad he chose this way.
Interesting puzzle, but I fear I would constantly make mistakes about assuming squares being fixed when in fact they aren't.
Day 2 of asking for you to make and use night mode on your software
Just turn the brightness down on your computer??
19 mins for me. I started in the bootom right corner, but with the same logic.
Me too (8 minutes being too lucky afterwards)
Almost completed it in half an hour but then made a mistake at the final hurdle. 😭
3:58. Terribly slow! (For me, that is). Kurotto is definitely a type that deserves more recognition.
That is a sick time!
@@CrackingTheCryptic It seems most of the solvers in the comment section got it in under 20 minutes. I got it in 8 minutes, but 3:58 is really a fast time.
so. its basicly minesweeper?
The main difference is that in minesweeper all nonmine cells have a clue but thats not true here. Also its not adjacent shaded cells but contiguous regions. Also mistakes allowrd
Your “check” button does NOT like this puzzle 😀
You really need to buy a microphone. Anything would be better than what you're using now.