The New Sudoku Players' Forum

by **Kent** » Fri Mar 17, 2006 3:37 pm

any suggestion??

5 1 . | . . 3 | 9 . 4
. 4 . | . . 5 | . 3 1
6 . 3 | 1 4 .| 5 . .
------+-------+-------
8 3 1| . . . | 4 . .
. . 9 | 3 1 .| 7 . .
. . 6 | . . . | 1 2 3
------+-------+-------
3 . 4| . 2 1 | . . 5
1 8 .| 9 5 . | 3 4 .
. . 5 | 4 3 . | . 1 .

by **MCC** » Fri Mar 17, 2006 5:23 pm

This is the third posting of the same puzzle, you've posted Here and Here, there is no need for this.

If you keep everything in the same thread then we'll be better able to help you.

Also, there is a candidate grid in the last link, your first post.

MCC

by **Kent** » Fri Mar 17, 2006 5:42 pm

MCC

there is a candidate grid in the last link

What do u mean candidate grid???

This is a totally new puzzle.I am sorry I made a mistake by posting same puzzle on different thread.

by **vidarino** » Fri Mar 17, 2006 5:50 pm

The candidate grid:

Code: Select all: 5 1 278 | 2678 678 3 | 9 678 4 279 4 278 | 2678 6789 5 | 268 3 1 6 279 3 | 1 4 2789 | 5 78 278 ----------------------+-----------------------+----------------------- 8 3 1 | 2567 679 2679 | 4 569 69 24 25 9 | 3 1 2468 | 7 568 68 47 57 6 | 578 789 4789 | 1 2 3 ----------------------+-----------------------+----------------------- 3 679 4 | 678 2 1 | 68 6789 5 1 8 27 | 9 5 67 | 3 4 267 279 2679 5 | 4 3 678 | 268 1 26789

Without it it's hard to tell which eliminations you have done before getting stuck. There are several box/line interactions (locked candidates) here, but we can't say which one you have found yet without knowing your candidates.

This is a pretty hard puzzle, by the way. Your next move, after several of the above-mentioned box/line eliminations, could be to locate a finned X-Wing in 6s.

It gets a bit tougher after that, though.

Vidar

by **Kent** » Fri Mar 17, 2006 7:24 pm

Code: Select all: 5 1 278 | 2678 678 3 | 9 678 4 279 4 278 | 2678 6789 5 | 268 3 1 6 279 3 | 1 4 2789 | 5 78 278 ----------------------+-----------------------+----------------------- 8 3 1 | 2567 67 267 | 4 569 69 24 25 9 | 3 1 46 | 7 568 68 47 57 6 | 578 789 489 | 1 2 3 ----------------------+-----------------------+----------------------- 3 679 4 | 678 2 1 | 68 6789 5 1 8 27 | 9 5 67 | 3 4 267 279 2679 5 | 4 3 678 | 268 1 26789

I'm sorry.This s the candidate grid i'm at.I'm stuck here

by **Guest** » Sat Mar 18, 2006 2:11 am

512|873|964
748|695|231
693|142|578
---------------
831|267|459
259|314|786
476|589|123
----------------
364|721|895
187|956|342
925|438|617

by **Cec** » Sat Mar 18, 2006 3:08 am

Hi canigia,
I'm sure you think you are helping by posting the solution but the forum is for "helping to solve" the puzzle. Simply posting the solution does nothing to teach anyone how to solve it. There are ample solver programs available which can provide an immediate solution to a puzzle but few of us, if any, can get excited doing that. If you look back through the forum's posts you'll see how solving techniques are posted and you are of course welcome to do that but please refrain from posting future solutions.
Cec

by **QBasicMac** » Sat Mar 18, 2006 4:26 am

After Locked candidate 2 in box 4, 7 in box 4, 8 in box 6 and 9 in box 6, you should get here:

Code: Select all: +----------------+------------------+------------------+ | 5 1 278 | 2678 678 3 | 9 678 4 | | 279 4 278 | 2678 6789 5 | 268 3 1 | | 6 279 3 | 1 4 2789 | 5 78 278 | +----------------+------------------+------------------+ | 8 3 1 | 2567 67 267 | 4 569 69 | | 24 25 9 | 3 1 46 | 7 568 68 | | 47 57 6 | 58 89 489 | 1 2 3 | +----------------+------------------+------------------+ | 3 679 4 | 678 2 1 | 68 6789 5 | | 1 8 27 | 9 5 67 | 3 4 267 | | 279 2679 5 | 4 3 678 | 268 1 26789 | +----------------+------------------+------------------+

Where I join you in Stuckville.

Mac

by **Kent** » Sat Mar 18, 2006 5:58 am

Mac, you're stuck here too??

by **vidarino** » Sat Mar 18, 2006 9:44 am

Code: Select all: 5 1 278 | 2678 678 3 | 9 678 4 279 4 278 | 2678 6789 5 | 268 3 1 6 279 3 | 1 4 2789 | 5 78 278 ----------------------+-----------------------+----------------------- 8 3 1 | 2567 67 267 | 4 569 -69 24 25 9 | 3 1 *46 | 7 #568 *68 47 57 6 | 58 89 489 | 1 2 3 ----------------------+-----------------------+----------------------- 3 679 4 | 678 2 1 | 68 6789 5 1 8 27 | 9 5 *67 | 3 4 *267 279 2679 5 | 4 3 678 | 268 1 26789

A good, old Finned X-Wing in R58C69 + fin in R5C8, eliminates the 6 in R4C9.

As mentioned, this is a pretty tough one. It gets worse...

by **Kent** » Sat Mar 18, 2006 10:47 am

Thanks vidar.Didnt really see that one.Just curious how long did u take to see that one??? Do u try to look out for other methods like colouring, forced chains before looking for x-wing?

by **vidarino** » Sat Mar 18, 2006 11:31 am

I cheated. I used my solver program this time. ;)

But normally, when solving moderately tough puzzles I filter digits one by one, looking for X-Wings, Swordfishes and doing basic coloring in my head (a.k.a. looking for X-Cycles - which sometimes leads to loops that double as finned fish, even). If that fails, I usually move on to bivalue / XY-Chains, and if that fails, more complex nice loops. (I'm not too great at figuring those out yet, though.)

One thing I have absolutely NO mastery in yet is the detection of Almost Locked Sets (which this puzzle will require, as far as I (or my solver) can tell).

by **Carcul** » Sat Mar 18, 2006 1:18 pm

Code: Select all: *--------------------------------------------------------------------* | 5 1 278 | 2678 678 3 | 9 678 4 | | 279 4 278 | 2678 6789 5 | 268 3 1 | | 6 279 3 | 1 4 2789 | 5 78 278 | |----------------------+----------------------+----------------------| | 8 3 1 | 2567 67 267 | 4 569 69 | | 24 25 9 | 3 1 46 | 7 568 68 | | 47 57 6 | 58 89 489 | 1 2 3 | |----------------------+----------------------+----------------------| | 3 679 4 | 678 2 1 | 68 6789 5 | | 1 8 27 | 9 5 67 | 3 4 267 | | 279 2679 5 | 4 3 678 | 268 1 26789 | *--------------------------------------------------------------------*

-7-[r7c4|r7c7]-6-[r7c2]=6=[r9c2]-{Nice Loop: [r5c9]=8=[r5c8]=5=[r4c8]-5-[r4c4]=5=[r6c4]-5-[r6c2]-7-[r7c2]=7=[r7c8]=9=[r9c9]-9-[r4c9]-6-[r5c8|r5c9]}-6-[r5c8|r5c9]-5-[r5c2]=5=[r6c2]-5-[r6c4]-8-[r6c5]-9-[r2c5]=9=[r2c1]-9-[r9c1]=9=[r9c9]-9-[r4c9]-6-[r8c9]=6=[r8c6]-6-[r5c6]-4-[r5c1]-2-[r5c2]

which means that, if r7c4 is not "7" then r5c2 turns out to be an empty cell - a contradiction. So, r7c4=7 and that solve the puzzle.

Carcul

by **ravel** » Sat Mar 18, 2006 4:48 pm

After Vidars finned x-wing you come here

Code: Select all: *-----------------------------------------------------------* | 5 1 278 | 2678 678 3 | 9 678 4 | | 279 4 78 | 678 6789 5 | 268 3 1 | | 6 279 3 | 1 4 2789 | 5 78 28 | |-------------------+-------------------+-------------------| | 8 3 1 | 2567 67 267 | 4 56 9 | | 24 25 9 | 3 1 46 | 7 568 68 | | 47 57 6 | 58 89 489 | 1 2 3 | |-------------------+-------------------+-------------------| | 3 67 4 | 678 2 1 | 68 9 5 | | 1 8 27 | 9 5 67 | 3 4 267 | | 279 2679 5 | 4 3 678 | 268 1 2678 | *-----------------------------------------------------------*

and can use this loop:
r3c6(=2=r4c6=7)-9-r3c2=9=r2c1-9-r9c1=9=r9c2=6=r7c2-6-r7c8-8-r7c4-7-r89c6
=>r6c6=9
That means, if r3c6=9, then
1. r4c6=2 <> 7
2. r2c1=9 and r9c2=9, r7c2=6 (col 2), r7c7=8, r7c4=7 and r89c6<>7
Then there is no 7 left in column 6.

by **QBasicMac** » Sat Mar 18, 2006 5:39 pm

I tried 8 in r6c5, which led to a solution easily.

So I tried 9. That was more fun, with several interesting locked candidates. But I eventually got to here

Code: Select all: +-------------+--------------+-----------+ | 5 1 278 | 27 78 3 | 9 6 4 | | 9 4 78 | 67 678 5 | 2 3 1 | | 6 2 3 | 1 4 9 | 5 8 7 | +-------------+--------------+-----------+ | 8 3 1 | 567 67 2 | 4 9 69 | | 24 2 9 | 3 1 46 | 7 5 68 | | 47 57 6 | 58 9 48 | 1 2 3 | +-------------+--------------+-----------+ | 3 9 4 | 68 2 1 | 68 7 5 | | 1 8 27 | 9 5 67 | 3 4 26 | | 27 6 5 | 4 3 78 | 8 1 29 | +-------------+--------------+-----------+

with 2 candidates 2 in column 2. That is two [stet] funny!

Anyway, thus there is only one solution.

I post this mainly to ask if there is a good way to distinguish between cells with a single candidate and cells that have been solved.

Maybe

Code: Select all: +-------------+ | 5 1 278 | | 9 4 78 | | 6 {2} 3 | +-------------+

I would hate to put brackets around all candidate lists as it scrolls off the right of the page more than ever when there are many cells with multiple candidates.

Mac

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