The New Sudoku Players' Forum

[BigG]

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


I stuck at this point. Can anyone help me with this one?

Thanks

[wintder]

This is the probable original.

Code: Select all

.78....2.
...8....6
13..2....
4..6.....
.9.2.5.1.
.....8..3
....1..52
3....7...
.5....39.

It is icky for me.

Here is the solution.

It is a very hard puzzle, not likely to have been one published.

Code: Select all

978163425
524879136
136524987
485631279
793245618
261798543
849316752
312957864
657482391

[BigG]

I can get the answer by using the "SudokuSusser" or any other sudoku software. But none of them can give me hint about how to find the solution.

[Steve K]

Here is the path I found - an interesting puzzle!
1) 24 givens. singles to 27 filled
2a) (1)r2c7=(1)r2c6-(1)r1c4=(1-7)r6c4=(7)r3c4-(7)r2c5=(7)r2c7 loop=>
r1c6<>1, r6c4<>9,r2c7<>459
2b) (6=pair39)r7c46-(9=triple678)r579c1-(6)r1c1=(6)r3c3 => r3c6<>6 => (6)r3c3
3a) Locked 4s r2c23 => r2c56<>4
3b) (7)r3c4=(7)r2c5-(7=1)r2c7-(1=9)r2c6 => r3c4<>9
3c) (1)r4c6=(1)r2c6-(1=7)r2c7-(7)r7c7=(7)r9c9-(7=1)r9c3 => r4c3<>1
3d) (6)r9c1=(6-8)r9c5=(8-5)r8c5=(5)r8c4-(5=7)r3c4-(7)r2c5=(7)r2c7-(7)r7c7=(7)r9c9
=> r9c1<>7
3e) (8)r5c1=(8-1)r4c2=(1)r4c6-(1=7)r4c4-(7=5)r3c4-(5)r8c4=(5-8)r8c5=(8)r9c5 =>
r9c1<>8 singles to 42 filled cells
4a) Locked 7s r6c45 => r6c137<>7
4b) (7): r5c1=r5c9-r9c9=r9c3 => r7c1,r4c3<>7 singles to end
I did not include some "easy" steps that I found but were not required.
Edit, one typo found in bold above.

[BigG]

I could not match the cells in the puzzle.

[hobiwan]

A possible solution with ALS:

From your grid, Locked Candidates (4 in b5), Hidden Triple (259 in b6) and Finned X-Wing (6 c28 r68 f[r7c2]) lead to:

Code: Select all

.---------------------.---------------------.---------------------.
| 569    7      8     | 1359   3569   13469 | 1459   2      1459  |
| 259    24     2459  | 8      579    149   | 14579  3      6     |
| 1      3      4569  | 579    2      469   | 45789  478    45789 |
:---------------------+---------------------+---------------------:
| 4      128    12357 | 6      379    139   | 259    78     59    |
| 678    9      367   | 2      347    5     | 4678   1      478   |
| 2567   126    12567 | 179    479    8     | 259    467    3     |
:---------------------+---------------------+---------------------:
| 6789   468    4679  | 39     1      369   | 4678   5      2     |
| 3      12468  1249  | 59     5689   7     | 1468   468    148   |
| 678    5      167   | 4      68     2     | 3      9      178   |
'---------------------'---------------------'---------------------'

Here I have the same chain as Steve K (just different notation and starting point):
Continuous Nice Loop [r1c4]=1=[r6c4]=7=[r3c4]-7-[r2c5]=7=[r2c7]=1=[r2c6]-1-[r1c4] => [r1c6]<>1, [r2c7]<>459, [r6c4]<>9

Then (equivalent to Steve's chain 2b):
Almost Locked Set XY-Chain: A=[r3c46789] - {456789}, B=[r7c46] - {369}, C=[r579c1] - {6789}, D=[r12c1],[r2c23] - {24569}, RCs=6,9, X=4,5,9 => [r3c3]<>4, [r3c3]<>5, [r3c3]<>9

Naked Single (6) and Locked Candidates (4 in b1) lead to:

Almost Locked Set XY-Wing: A=[r1c1479] - {13459}, B=[r2347c6] - {13469}, C=[r78c4],[r89c5] - {35689}, Y,Z=3,6, X=4,9 => [r1c6],[r3c789]<>4, [r1c6]<>9

Hidden Single (4), Naked Pair (78 in c8)

Skyscraper: 7 in [r4c8],[r6c4] (verbunden durch [r3c48]) => [r4c5]<>7
X-Chain: 6 [r8c8]=6=[r6c8]-6-[r5c7]=6=[r5c1]-6-[r9c1]=6=[r9c5] => [r8c5]<>6
Discontinuous Nice Loop [r3c4]=7=[r6c4]=1=[r1c4]-1-[r2c6]-9-[r3c4] => [r3c4]<>9
Locked Candidates Type 2 (Claiming): 9 in r3 => [r1c79]<>9
Discontinuous Nice Loop [r4c2]-1-[r4c6]=1=[r2c6]-1-[r2c7]-7-[r3c8]-8-[r4c8]=8=[r4c2] => [r4c2]<>1
W-Wing: 7 in [r6c4],[r9c3] verbunden durch 1 in [r4c36] => [r6c3]<>7
Sashimi Swordfish: 1 r249 c369 f[r2c7] => [r1c9]<>1
Locked Candidates Type 1 (Pointing): 1 in b3 => [r8c7]<>1
Discontinuous Nice Loop [r4c6]=1=[r4c3]-1-[r9c3]-7-[r9c9]=7=[r7c7]-7-[r2c7]-1-[r2c6]=1=[r4c6] => [r4c6]<>3, [r4c6]<>9
Singles

There are more steps in total, but some of them are rather easy.

[Steve K]

I hope it is a solution to the puzzle you posted..... I may be guilty of dyslexic typos, but otherwise the solution path should be ok.

Code: Select all

 puzzle with pencil marks:

 
 *-----------------------------------------------------------------------------*
 | 569     7       8       | 1359    34569   13469   | 1459    2       1459    |
 | 259     24      2459    | 8       4579    149     | 14579   3       6       |
 | 1       3       4569    | 579     2       469     | 45789   478     45789   |
 |-------------------------+-------------------------+-------------------------|
 | 4       128     12357   | 6       379     139     | 25789   78      5789    |
 | 678     9       367     | 2       347     5       | 4678    1       478     |
 | 2567    126     12567   | 179     479     8       | 245679  467     3       |
 |-------------------------+-------------------------+-------------------------|
 | 6789    468     4679    | 39      1       369     | 4678    5       2       |
 | 3       12468   12469   | 59      5689    7       | 1468    468     148     |
 | 678     5       167     | 4       68      2       | 3       9       178     |
 *-----------------------------------------------------------------------------*


Code: Select all

(1)r2c7=(1)r2c6-(1)r1c4=(1-7)r6c4=(7)r3c4-(7)r2c5=(7)r2c7 loop=>
r1c6<>1, r6c4<>9,r2c7<>459
 *-----------------------------------------------------------------------------*
 | 569     7       8       | 1A359   34569   13469   | 1459    2       1459    |
 | 259     24      2459    | 8       457B9   1a49    | 1A457b9 3       6       |
 | 1       3       4569    | 57b9    2       469     | 45789   478     45789   |
 |-------------------------+-------------------------+-------------------------|
 | 4       128     12357   | 6       379     139     | 25789   78      5789    |
 | 678     9       367     | 2       347     5       | 4678    1       478     |
 | 2567    126     12567   | 1a7B9   479     8       | 245679  467     3       |
 |-------------------------+-------------------------+-------------------------|
 | 6789    468     4679    | 39      1       369     | 4678    5       2       |
 | 3       12468   12469   | 59      5689    7       | 1468    468     148     |
 | 678     5       167     | 4       68      2       | 3       9       178     |
 *-----------------------------------------------------------------------------*


Code: Select all

(6=pair39)r7c46-(9=triple678)r579c1-(6)r1c1=(6)r3c3 => r3c6<>6 => (6)r3c3
 
 *-----------------------------------------------------------------------------*
 | 56a9    7       8       | 1359    34569   3469    | 1459    2       1459    |
 | 259     24      2459    | 8       4579    149     | 17      3       6       |
 | 1       3       456A9   | 579     2       4-69    | 45789   478     45789   |
 |-------------------------+-------------------------+-------------------------|
 | 4       128     12357   | 6       379     139     | 25789   78      5789    |
 | 6A78    9       367     | 2       347     5       | 4678    1       478     |
 | 2567    126     12567   | 17      479     8       | 245679  467     3       |
 |-------------------------+-------------------------+-------------------------|
 | 6A789b  468     4679    | 39B     1       36a9B   | 4678    5       2       |
 | 3       12468   12469   | 59      5689    7       | 1468    468     148     |
 | 6A78    5       167     | 4       68      2       | 3       9       178     |
 *-----------------------------------------------------------------------------*



etc. Not very good at the graphics here (or anywhere),