sudoku

[kyrax12]

Just got started playing

It is pretty addicting

Are you supposed to be erasing a lot?

 

[DaTT]

never erase, there's no need too.

 

[Loop2kil]

I started playing a few weeks ago myself...the easy levels were too easy so I started with the medium level. I play on my phone so I've completed 100 medium and 100 challenging....only a few into the hard and I can see i will need a scratch pad to finish these.

But yeah the game is quite addicting

 

[kyrax12]

never erase, there's no need too.

Lol what if you get to block/row with two or more possible answers?

 

[Soccerman06]

It doesnt really get hard unless you try to do it all in your head without a scratch piece of paper or writing in the corner

 

[AyashiKaibutsu]

It doesnt really get hard unless you try to do it all in your head without a scratch piece of paper or writing in the corner

There's advanced puzzles that are hard even with writing in the corners. Anything rated medium or easier you can generally work out just straight up process of elimination.

 

[GagHalfrunt]

Lol what if you get to block/row with two or more possible answers?

Then you move on to a different spot. The games are never blind guesses, there's always a definitive move to be made. If you don't see it you're either not looking deeply enough at that spot or you're looking in the wrong place.

 

[silverpig]

I hate the ones where the only way to proceed is to guess and then see what happens.

 

[PowerEngineer]

I've found that I like adduko (aslo known as "Killer SudoKu") better.

http://www.dailykillersudoku.com/

Have fun!

 

[silverpig]

Then you move on to a different spot. The games are never blind guesses, there's always a definitive move to be made. If you don't see it you're either not looking deeply enough at that spot or you're looking in the wrong place.

Not true. There are some instances where you just have to guess because you can't determine anything from what you have. Sometimes you'll get a square where there can be either a 2 or a 3 but you don't know which and can't tell until you guess, then fill out the next 5-6 squares based on that knowledge and you go until you reach a contradiction or you solve the puzzle.

 

[AyashiKaibutsu]

I hate the ones where the only way to proceed is to guess and then see what happens.

There's a way to logic through all of them from what I've seen.

http://www.sudokudragon.com/advancedstrategy.htm

Although once they get that hard I'm usually too lazy to try to solve them.

 

[GagHalfrunt]

Not true. There are some instances where you just have to guess because you can't determine anything from what you have. Sometimes you'll get a square where there can be either a 2 or a 3 but you don't know which and can't tell until you guess, then fill out the next 5-6 squares based on that knowledge and you go until you reach a contradiction or you solve the puzzle.

Wrong. Totally wrong. The fact that you don't see the next move doesn't mean it's not there. You might have to logic out an entire row or column to be able to solve a block in a totally unrelated cell, but it's always doable without guessing. The next time you get to a spot that you can't get out of post the puzzle here. I guarantee that someone will find the right answer based on pure logic with no guesswork involved.

 

[Lifted]

I play on my phone every day on hard and never once needed a scratch pad. You're simply not thinking it through. There are a few different strategies you pick up along the way, so perhaps you haven't figured them out yet. Guessing is not what this game is about. There is always a correct box to fill in.

 

[Aikouka]

I usually play Mathdoku/Kenken more than Sudoku. I find it significantly harder especially when you jump up to 9x9 puzzles with no operators.

Here's an example of a 9x9 puzzle with no operators:
http://mathmojo.com/chronicles/wp-content/uploads/2009/01/9-x-9-kenken-3.png

Sometimes it's easy to tell the operator simply by having the result and the number of blocks available, but other times, it's not nearly as easy to deduce whether it's addition or multiplication. That's especially the case if the blocks do not occupy a single vertical or horizontal line (numbers cannot repeat just like in Sudoku).

If you have an iPhone or iPod Touch, I'd recommend this version of it:
http://itunes.apple.com/us/app/kenken-pro-by-will-shortz/id363198920?mt=8

There's a way to logic through all of them from what I've seen.

I don't play Sudoku nearly as much as I play Kenken (also called Mathdoku), but I've run into issues such as no guaranteed plays (which is much harder to deduce in Kenken with no operators) and multiple solutions. The issue with the latter is that games on the phone or whatever are only designed to accept one solution, and when I enter a valid solution that isn't the one pre-programmed into the game, it will not accept it. I usually triple check them before I grumble a bit and reset the enter board.

 

[silverpig]

Wrong. Totally wrong. The fact that you don't see the next move doesn't mean it's not there. You might have to logic out an entire row or column to be able to solve a block in a totally unrelated cell, but it's always doable without guessing. The next time you get to a spot that you can't get out of post the puzzle here. I guarantee that someone will find the right answer based on pure logic with no guesswork involved.

http://entertainment.howstuffworks.com/leisure/brain-games/sudoku4.htm

http://www.sudokudragon.com/sudokuguess.htm

http://books.google.ca/books?id=1TU...q=sudoku%20that requires guessing&f=false

http://forum.caravelgames.com/viewtopic.php?TopicID=29360

 

[ockky]

I hate the ones where the only way to proceed is to guess and then see what happens.

ditto. once i realized that puzzles existed that you couldn't mathematically solve, i got pissed off and quit...whats' the point?!

 

[Aikouka]

ditto. once i realized that puzzles existed that you couldn't mathematically solve, i got pissed off and quit...whats' the point?!

I think that's the problem that I run into with physics based games as well. I recall playing this game on my phone (Tumble Drop), and I knew the way to solve the puzzle, but it wouldn't work the first time or two. I did pretty much the exact same thing a third time and it worked flawlessly. Hitting something a 100 milliseconds later can drastically alter the events in these games, which makes them somewhat irritating at times. I really enjoy Trine, but I ended up never finishing it because of how much physics puzzles tend to grate me.

 

[TuxDave]

I've found that I like adduko (aslo known as "Killer SudoKu") better.

http://www.dailykillersudoku.com/

Have fun!

Wow, that took me 30 minutes to solve a 1/10. sheesh..... a totally different way of thinking to solve that.

 

[destrekor]

I hate the ones where the only way to proceed is to guess and then see what happens.

Those don't exist.

When I've reached a point where I can't find a single definitive spot, I move on to another puzzle. Sometimes a few days provides a fresh set of eyes that will see something you missed.

That can be hard when you use pen notes (on paper puzzles) in the corners. When you look at it after a long time, it's even worse looking at the puzzle.

Most Medium and some Hard puzzles I won't use notes, or may at most use one or two notes early for a few squares.
Most Super Hard puzzles I'll have nearly the whole puzzle scattered with notes.


But the short answer to the OP:
There is one solution to the puzzle - no square will have more than one correct number. If a square appears that way at one point in time, it's because you have not discovered enough solutions to deduce that specific box just yet. Myriad combinations across the whole puzzle can unlock any given box.

Sometimes I seem to find a wall where I can find no further solutions; Sometimes I literally have to give up, especially when I'm feeling foggy headed and attempting some of the harder puzzles out there.
One of the few pleasures of my shitty (unrelated) job. I can put hours into puzzles (or reading, or whatever is not delivered by an electronic device ) and sometimes only have less than 10 minutes of interruptions in an hour.
Sometimes I have put more than two hours of time into a single puzzle before I solved it. I'm stubborn and hate quitting, so I have to have spent a good time staring at it, stabbing for answers, before I give up. Sometimes that persistence pays off and I find a key answer that goes on to make a whole ton jump out at me.

 

[gorobei]

you are not supposed to guess.

there are advanced leveled cases where matched pairs of spaces in 2 grid blocks can go either way(i.e. 7&4 in one grid, and 4&7 in the other grid; and vice versa).
while it seems like the only way to solve is to fill in one case and see if it works and then go back to the other case if it doesnt, that isnt the way you are meant to solve it. the fact that you know 2 specific numbers occupy those spots on the two 9x9 grids (though not the exact arrangement) is meant to allow you to eliminate them from contention for other spots in the grid. you use that information as a process of elimination so the other numbers/spots can be solved.

 

[radhak]

All those who are claiming that 'guess' is never a part of the strategy, please visit the links posted by silverpig above (esp the second link http://www.sudokudragon.com/sudokuguess.htm). As explained there, some sudoku puzzles are built with the idea that guessing will be required, and Michael Mepham has now decided to not publish such puzzles to avoid the angst among his readers. The puzzle posted in that page is a good example - please see if you can solve it without 'guessing'.

I do have an observation about 'guessing' : it is what you are doing many a times when working it mentally without writing it down (and you think you are only following 'logic') when you argue, "okay, if this were a 6, then this other spot will have to be a 7, but that would mean this next box can only be a 9, forcing the 6 on the next row here, which conflicts with the original 6 I put down." < I am sure you are not doing this, but just saying...>

But any which way, in today's day and age I am pleasantly surprised so many are interested in such puzzles that exercise the mind. At work, I am surrounded by reality show addicts - scary by itself !

 

[kranky]

I do these puzzles once in a while. Sometimes I get stuck about halfway through and can't finish. I won't write down anything to help solve it and I won't guess, that's just the way I decided to work on them.

 

[silverpig]

you are not supposed to guess.

there are advanced leveled cases where matched pairs of spaces in 2 grid blocks can go either way(i.e. 7&4 in one grid, and 4&7 in the other grid; and vice versa).
while it seems like the only way to solve is to fill in one case and see if it works and then go back to the other case if it doesnt, that isnt the way you are meant to solve it. the fact that you know 2 specific numbers occupy those spots on the two 9x9 grids (though not the exact arrangement) is meant to allow you to eliminate them from contention for other spots in the grid. you use that information as a process of elimination so the other numbers/spots can be solved.

Welcome to intermediate strategies in sudoku

Once you try the super hard ones you'll find some that require guessing. Not all do, but there definitely are some.

In fact, I think a valid sudoku puzzle only requires that it be self-consistent, not necessarily unique. That is, a given starting position may yield more than one solution. In this case it is required that you guess as there is by definition no single logical solution.

And by guessing I mean the memory stack you have to use to determine consistency is longer than what you can keep track of in your brain; usually the remainder of the puzzle.

 

[thereds]

sudoku - helping dumbasses think they're doing advanced math.

 

[TecHNooB]

Something I find useful is determining at minimum which row or column a number is in and using that information to make other eliminations. Often, you can't determine exactly what position that number is within that row or column but you can use that row/column info to make eliminations in other places.