Sudoku

[ItllBeLonelymumThisChristmas]

Who here does them in the Times or elsewhere?

I completed my first puzzle today with the help of my 8 yo son (who is gifted mathematically but all the same, he is only 8 FGS and I still found his support invaluable!)

It was the easy graded puzzle and I would like to try the "fiendish" one now. Any hints on how to complete it honestly?

Oooh - there was a thread someone else started asking this and people had loads of tips. I'll have a look...

Yes, I do them.! Not the Times, of course Have even completed the big Saturday one in the Indie a few times. My 8 year old can do them as well. Hints? Hmm, just practice. You can get books on techniques but they all have Carol Voderman's face on the cover, unfortunately.

Think it was this thread

Noooooooo! Not CV!

I had a look in recent threads, but couldn't find anything except passing mentions. No hints.

This is my method ... I can't get enough of the little blighters

Go across all of the horizontal bands placing numbers. Where there are two of one number in a band, you might be able to place the third. If you can, put it in and check whether you can use it to place any more vertically.

Go down all of the vertical bands placing numbers as for the horizontal bands.

Place any other numbers you can by process of elimination - start with the grids, columns or rows which have the smallest number of numbers to fit in. Write the numbers down alongside the grid so that you don't forget them, and cross them out as you find them.

Then, when you can't see any more obvious numbers to place, write into each box the numbers that could potentially be in that box. You can then check to see if there are any boxes in a 9x9 grid or in a column or row where there are only two numbers that could fit ... eg two squares which are either going to be 1 or 6. You can then eliminate those numbers from the rest of the 9x9 grid, row or column.

Check each 9x9 grid, then check each row and then each column to see if there are any numbers in each that only appear once. If there are you can place it, and eliminate it from the grid, row and column.

You can print the Times ones off here the day after they appear in the paper

I do, but find it impossible to put into words how I do it . There were some good articles (with diagrams) in the Times when it first started- they might help.

I love them, it's a great way to relax. The only way to get better is to practice imho.

How did I miss that thread when I looked in the archives just now?

Anyway, WWB, I follow your method (as far as I understand it! ) but have got stuck on the harder puzzle because I just can't find any box I can definitely fill in if that makes sense? I can't guess a number (say if I know it must be one of two) as that guess wo8uld determine all the other answers. Surely every puzzle must be fill-inable without making any blind guesses?

If you know that there could only be one or two numbers in one box, write them in at the top of the box or in pencil - if you do that for all of the boxes you might find that there are some obvious numbers that can be eliminated. When you then check the numbers you're left with, there might be only one square in a 9x9 grid that has one number in it, for example. Or you might find that there are two squares which could contain only the same two numbers - if two squares are either 1 or 2 then you know they won't be anywhere else in that 9x9 grid.

Yes, you're right- certainly in the Times they are all meant to be done without any guesses. They talk in that article about "slice and dice" which is quite a useful concept if you can follow it!

So you never ever write a number in as a pure guess?

I have just printed out yesterday's Times puzzle and am off to try the simple one on my own before coming back to the fiendish one!

Also, if two squares are either 1 or 2 then nothing else can go in those 2 squares which can narrow things down.

No, you should never need to guess.

LM, you might be better off getting a Times Sudoku book that starts easy and works its way up to the fiendish - rather than just throwing yourself at the mercies of the fiendish ones! They gradually get harder and you find yourself coming up with your own methods of doing them as you practice on the easy, mild and difficult ones first!

No, never guess unless you are fed up and want it to end one way or another! I've found a good compliation of tips here . The fiendish one in today's paper actually had a lot of numbers that could be filled in straight away and there was hardly any need for writing in alternatives, so it would definitely be worth looking at some rules/tips.

If, when you pencil in your "possible numbers" you end up with one 3x3 box where a number (in this case the bold 2) is the only one in a particular row, you know that it must go there, regardless of the other possible locations for it in that box. In this example, neither of the other 3x3 boxes in that row have a 2 in the middle as a possibility.

xxx x2x x2x
x2x xxx xxx
x2x x2x x2x

does that make any sense whatsoever?? I know what I mean

The Times website is good as it has both easy and more difficult (and Killer which I love ) available.

I feel the need to update mn - just for purposes of editorial accuracy you understand - not bragging! On that other thread I confessed that I couldn't do the Samurai Sudoku ...

... well I now can

Have just completed yesterdys easy puzzle in 35 minutes. Go on, now tell me you regulars do it in 5!

Just as well I was not doing it somewhere public though (thinking of on a train) as I was incapable of doing it without muttering out loud "If 2 goes there then it can't go there, but there it is there so it must be in there..." etc etc. It would drive anyone sitting near me nuts!

I have got a book of puzzles I bought for ds2 to do but he doesn't do them usually, so I will search it out.

I love the Indie ones. Bought aTimes book for last hols. The hard ones are fiendish. I erasered the page before I managed to finish one!

I find 2 glasses of red wine help enormously.

Another sudoku nutter here. Have just about got the hang of x-wings, but can anyone properly explain swordfish to me?