Discuss the <a href="http://www.sudocue.net/daily.php">Daily Sudoku Nightmare</a> here
CathyW
Master
Posts: 161 Joined: Wed Jan 31, 2007 5:39 pm
Location: Hertfordshire, UK
Post
by CathyW » Mon Apr 30, 2007 8:49 pm
It's only Monday! I've got this far.
Code: Select all
+-----------------+--------------+-----------------+
| 1238 1238 4 | 9 167 78 | 2367 5 1678 |
| 1358 7 13589 | 16 2 58 | 369 1689 4 |
| 6 1258 12589 | 14 1457 3 | 279 1789 1789 |
+-----------------+--------------+-----------------+
| 9 2345 235 | 8 347 6 | 1 47 57 |
| 158 6 158 | 24 479 279 | 4579 3 5789 |
| 38 348 7 | 5 349 1 | 469 4689 2 |
+-----------------+--------------+-----------------+
| 1258 1258 12568 | 7 1569 259 | 4569 1469 3 |
| 4 135 1356 | 136 8 59 | 5679 2 15679 |
| 7 9 23 | 23 156 4 | 8 16 156 |
+-----------------+--------------+-----------------+
Edit: Checked the page - it's still Sunday's puzzle - no wonder I can't do it!!
Ruud
Site Owner
Posts: 601 Joined: Fri Dec 30, 2005 10:21 pm
Post
by Ruud » Mon Apr 30, 2007 9:23 pm
Oops I did it again!
New puzzles have been uploaded, including a mondayish Monday puzzle.
Ruud
“If the human brain were so simple that we could understand it, we would be so simple that we couldn't.” - Emerson M Pugh
CathyW
Master
Posts: 161 Joined: Wed Jan 31, 2007 5:39 pm
Location: Hertfordshire, UK
Post
by CathyW » Tue May 01, 2007 8:47 am
Thanks Ruud
If anyone would care to explain how the Sunday puzzle can be solved, I'd like to learn more.
GreenLantern
Regular
Posts: 14 Joined: Tue May 30, 2006 8:07 pm
Post
by GreenLantern » Tue May 01, 2007 1:39 pm
Here is how I ended up solving the puzzle from your starting candidates grid.
For a good tutorial on Nice Loops for those unfamiliar with the notation, please refer to
Paul's Nice Loop Guide .
[r7c6]=2=[r5c6]-2-[r5c4]-4-[r3c4]=4=[r3c5]=5=[r2c6](-5-[r7c6])-5-[r8c6]-9-[r7c6] => r7c6<>59
[r2c1]=3=[r6c1]-3-[r6c5]-9-[r5c6]-7-[r1c6]-8-[r2c6]-5-[r2c1] => r2c1<>5
[r7c1]=5=[r5c1]-5-[r4c3]-3-[r6c1]-8-[r7c1] => r7c1<>8
[r5c5]=4=[r5c7]=5=[r78c7]-5-[r9c9]=5=[r9c5]-5-[r8c6]-9-[r5c6]-7-[r5c5] => r5c5<>7
[r4c5]=3=[r4c3]=5=[r4c9]-5-[r9c9]=5=[r9c5]-5-[r8c6]-9-[r5c6]-7-[r4c5] => r4c5<>7
Multicoloring in 1's: r18c2,r28c4 => r1c5/r2c13<>1
XY-wing (167): r1c59,r3c5 => r3c8<>1
Coloring in 1's: r1c29,r2c48,r8c24 => r8c3<>1
[r2c3]=9=[r3c3]-9-[r3c9]=9=[r5c9]=8=[r5c3]-8-[r2c3] => r2c3<>8
X-wing in 8's: r26c18 => r3c8<>8
[r1c7]=3=[r1c2]=1=[r3c3]-1-[r3c5]-7-[r1c5]-6-[r1c7] => r1c7<>6
[r7c3]=6=[r7c5]=1=[r3c5]=7=[r3c8]-7-[r4c8]-4-[r4c5]-3-[r4c3]-5-[r5c1]-1-[r7c1](-5-[r7c3])-5-[r7c2]-8-[r7c3] => r7c3<>58
[r2c8]=1=[r1c9]=6=[r1c5]=7=[r3c5]-7-[r3c8]-9-[r3c9]-8-[r2c8] => r2c8<>8
After solving the puzzle, I checked to see how the computer solved it, and here's the somewhat shorter, more efficient solution it came up with:
[r3c4]=4=[r3c5]=5=[r2c6]=8=[r1c6]=7=[r5c6]=2=[r5c4]=4=[r3c3] => r3c3=4
[r1c7]=3=[r1c2]-3-[r8c2]=3=[r8c3]-3-[r4c4]=3=[r4c5]-3-[r6c5]-9-[r6c7]-6-[r1c7] => r1c7<>6
Coloring in 6's: r1c59,r28c4 => r8c9<>6
[r1c2]-3-[r1c7]-7-[r8c7]=7=[r8c9]-7-[r4c9]-5-[r4c3]-3-[r8c3]=3=[r8c2]-3-[r1c2] => r1c2<>3
XY-wing (789): r1c6,r5c69 => r1c9<>8
XY-wing (579): r5c6,r8c67 => r5c7<>7
Coloring in 5's: r4c39,r57c7 => r7c3<>5
Multicoloring in 5's: r37c2,r4c39,r57c7 => r23c3<>5
[r1c6]=8=[r2c6]=5=[r2c1]=3=[r2c3]-3-[r4c3]=3=[r4c5]=4=[r5c5]=7=[r5c6]-7-[r1c6] => r1c6<>7
CathyW
Master
Posts: 161 Joined: Wed Jan 31, 2007 5:39 pm
Location: Hertfordshire, UK
Post
by CathyW » Tue May 01, 2007 4:09 pm
Thank you - I can see I shall have to study those nice loops more. I'm OK with conjugate pairs (though I still find it easier to use colouring to identify them) but I do get confused about strong/weak links. Thanks for pointer to Paul's guide - going to visit it now!