Looking for Sudoku Experts
 

We have a ritual at work... and that's playing sudoku every lunch time. XD

This evil puzzle got us stuck today... it felt like it went well... but we all got stuck at the same place (even our extra-expert boss who plays the entire thing without little numbers)

So... here's the challenge, if anyone could solve it!

Condition: NO GUESSING. Each square must be logically derived.

Original Puzzle# 2,647,758,044


We got stuck here!!
(Using a url tag so it doesnt spoil it for anyone who wants to start from scratch)

This is where we all got up to and got stuck, so if anyone could show us how u arrived at the next number (and assuming from that number onward, all other numbers will come into place)... Then i'll call u Expert from now on! XD

D: i'm no expert, this is evil

yay i put in a number :D

Added 2 numbers for you. I will keep staring at it for a bit.

http://i169.photobucket.com/albums/u...ps/Sudoku1.jpg

Oops - had to edit - I copied the wrong code.

Oh oh... we got the 8 and 9 too.. LOL! i just 4got to put it in for my screenshot :sigh:

EDIT: I've corrected my image... so its the same as Loki's now

i'm tired of trying to figure it out from scratch so maybe i'll just look at yours now >_<

o: we went two completely different ways, maybe i shouldn't have cleared my puzzle

=O different ways?!

Hmm I'm smelling something must be the brains frying in this topic :err:

Sudoku is torture I tell you :hulksmash:

:cheeky: I'm hopeless with crosswords so sudoku is my alternative~

I'm more logic than knowledge LOL


@Loki - Yup! Pencil figures welcomed!

I do that too..

Hmm so how did you arrive at the 7?

What stops the 7 from being in the 3rd column, 4th row?

(if that's a key point to getting the 7)

HAHA... thats ok!! I'll try work on it again on the train too...

GOOD NIGHT!!

Instructions to complete. Highlight to see. Solution is based on given point.

Warning: HUGE post.

1. It can be seen in the top three boxes that in the upper-right box, a 9 cannot be on the bottom two rows of that box. Therefore, 9 is in the top right-hand corner.

2. In the same box, it can be concluded that 6, 7, and 8 are the numbers required to complete it. In the top row, however, 6 and 7 are already present. This leaves 8.

3. Observe the middle box. The box lacks a 1, 4, 5, 6, 8, and 9. However, it can be seen that 4, 5, 6, 8, and 9 cannot fit in the middle box of the first row. Thus, 1.

4. In the same box, but on the bottom row, it can be observed that 4, 5, 6, and 9 are not applicable to that box, but 8 is.

5. In the fifth column, the number 5 can be filled because it is the only missing number in the column.

6. In the top left box, it can be observed that only 5 can only fit in the top right hand corner of that box. This allows 1 to be filled in the remaining box.

7. In the second column from the top overall, it can be seen that 6, 7, and 8 are lacking. However, 6 and 7 are in the middle box of the top row, so 8 can be filled in the one remaining box in the second row and second box.

8. This one is tough to explain. If you observe the bottom right box, you'll notice how 1 is confined to the seventh column from the left. Keeping that knowledge in mind, look up one box. It can be seen that 1 can only be in the middle box of that box.

9. Look at the box just under the top right box. It can be observed that 1 can only be in the middle box of the bottom row of that box. 9 can also be filled on top of that in the middle box of the middle row, since it completes the second column.

10. Observe the middle box. It can be seen that 9 can only be in the top left hand box of the middle box.

11. Look at the third box from the left in the second row. It can be observed that 9 can only be in the bottom left-hand box of that box.

12. Once again, observe the middle box. In the second row, first box, it can be deduced that 6 is the only integer that can fit in that box.

13. With this knowledge, look to the right box of the second row. It can be seen that 5 can only fit there, and 4 below it.

14. Look at the fourth column from the left. It can be seen that 1 and 4 are the only ones needed; however, it can also be seen that 4 cannot fit in the bottom box. Thus, 4 is on the top box and 1 is on the bottom box of the column. This also fills in 1 in the top row of the middle box of the top row.

15. In the bottom row of the bottom row of boxes, it can be seen that 2, 6, and 8 are the numbers needed. However, when looking at the bottom right box, it can be concluded that only 6 can go there.

16. Observe the bottom right box. It can be concluded that 1 can only be in the first box of the second row.

17. Observe the second row of the bottom row of boxes. It can be seen that 6, 7, and 8 are required. However, it can be deduced that 7 can only be in the bottom right box.

18. In the bottom right box of the bottom row, it can be seen 4 and 8 are required. Ergo, it can be seen that 8 can clearly not fit in the first box in the first row, thus 4 goes there and 8 goes in the remaining box. In the 7th column, 7 can also be placed to finish the column.

19. In the right box in the second row, it can be seen that 2, 3, 4, and 6 are required. However, in the second box in the first row, only 6 can fit. With this knowledge, it can be easily seen that 7 goes in the remaining box in the eighth row, and a 6 right next to it, completing the top right box.

20. In the left box in the second row, it can be seen that the far right box in the first row can only be a 2.

21. In the bottom left box, it can be seen that the only number that can go in the far right box in the first row is a 6. A 7 can also be placed above this number in the bottom right box of the third row of the left box of the middle row to complete the third column. The far right box of the first row of the middle box of the third row of boxes can also be filled with a 2 to complete the 7th row.

22. In the middle box of the third row of boxes, it can be seen that only an 8 can go in the bottom right box of the third row. Consequently, a 6 can go above it to finish the box.

23. I'm getting a bit tired, so I'll cut it short: Now, the bottom left box of the third row of boxes can be completed. Self-explanatory.

24. It can be seen in the left box of the second row in the first row that a 4 and 5 is required. However, the 4 in the first column cancels the 4 chance. Consequently, finish the row with putting a 5 in the first box of the fourth row and a 4 in the last box of the same row.

25. It can be seen in the left box of the middle row of the left box of the middle row of boxes that a 3 can only go there. Complete the row by finishing the last box in the same row with a 2.

26. I'm not sure why I'm writing this step, since there's two boxes left. Fill the box on the left with a 6, and the box on the right with a 3.

Congratulations, you are done. Total elapsed time: 01:04:26.

WOW!!!!! thx for writing all that out!!

-now takes my time reading it-

I'm half asleep right now, it's 1:38 AM in the morning, I wrote that as I went. So it may not be the easiest to understand, but I tried.

I omitted all my statistical analysis. Because the pattern in there hinted at the arrangement of the numbers, but you said strict logic, so I chugged through it as best as I could. :sigh:

Statistical analysis? as in.. the chances of a 1 being here and here is very likely? oh yeah cant do that..

I think i'll hv to print it out and read it on the train home... my boss is around so i cant sit around with a sudoku in front of me LOL!!

ok! you lost me here

My Middle Box

How did you derive that the middle column, 4th row cannot be a 5?

I figured it out... then... forgot to take a picture.

EDIT: Did it again...
http://img.photobucket.com/albums/v6...a/Untitled.jpg

I checked my piece of scribble paper. Evidently, when I was going through for that box, I typed "1, 4, 5, 6, 8, and 9" for the post, but on paper I forgot the 8. That explains how I mistakenly calculated it... :uhoh:

Aha, that is firsthand proof of how badly people mess up when they're tired.

the other option is to google sudoku solvers :p

XD but i want to know how u arrived at the answer.. from my sudoku picture..

=O i had so much faith in your solutions!

Description of www.sudokusolver.co.uk looks good (solve by logic) but it wont load for me ><

Well, the rule of sudoku is that every 3x3 square can only contain numbers 1-9. Each row across the whole 9x9 and column can only house numbers 1-9.

So if you have a 1 on the top left corner you can't have that same number across and down. It's hard to explain cause I just do it... lol. It's mostly a process of elimination and what fits. Usually if I have 3-4 empty boxes left I can figure out a whole 3x3, column or row... .__. Bleh.

hmmmmm i need to explain to my colleague how i got my answer... why a number has to be in that square and not another number........

I thought i've tried eliminating all the squares but.. nothing will come out ><

I've done really hard ones where you are left with boxes that you have to guess. Pretty much everything is left as it can be this or this. I go with the rule, nothing is every easy.

Then you get to the really hard ones that are like 5 sudokus in 1
or weird shapes that split each box into triangles or a hexagonal sudoku xD
and also sudoku which uses the alphabet
there are also those 3D cube sudokus too :zomg:
_____________________

I was bored at work...
here's my solution to the Sudoku
http://img50.imageshack.us/my.php?image=sudokuwr6.jpg

Hessah, I would LOVE to say that the answer (for everything, really) can be directly obtained by logical reasoning. However, the reality is that we sometimes have to resort to trials and errors. We can, though, limit the number of trials. In all sudokus of this level, I always manage to nail it down to 2 possible pathways. I try one and if it doesn't work, the other one is definitely the road to victory. The trick is to choose which 2 pathways. Usually, it's two boxes in one 3x3 square that one number can go in and if either box is filled, it must also reveal the others in the puzzle, until you encounter a contradiction where the same number turns up twice in a row, column or a 3x3 square (when you choose the wrong path) or complete the puzzle (if you happen to choose the correct path in the first place). If you make a bad choice, the box that is filled in won't lead to many others and you end up stuck again.

I think completing a sudoku with a trial and error is meaningless....

Coz you can punch in the number and click "Check" on the website anyway, so it kinda defeats the purpose of working it out.

If this is one of those where I have to do a trial and error then... this sudoku fails! HAHA

I was trying to see if anyone outside my office sees a logical way to solve this without having to guess. Coz i've watched my colleague work another Sudoku out a way that i've never used before, its like a new "strategy" that helps me work out new stuff, so... I was hoping that someone could open my eyes on other ways of thinking.

Thanks to those who's tried it for me!!!! :cheeky:

lol, not exactly. the way i said it means that you have to work out everything logically the whole way except the crucial step where you have two possible ways to get to the solution. As soon as you decide to take one route, it's logic all over again. So really, there's only one trial and error undertaken here (and to arrive at this stage is not obvious since you have to solve like half of the puzzle to see it). In the evil one, only one is the right one. In the diabolical one, BOTH ways give you the solution. I remember solving a few that have two solutions.

And I think I'm a bit like your boss, I rarely use small numbers because I know exactly which number goes in what cell.