Daily Nightmare - 30-4-07

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CathyW
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Daily Nightmare - 30-4-07

Post by CathyW »

:? 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
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Post by Ruud »

Oops I did it again! :oops:

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
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Post by CathyW »

Thanks Ruud :)

If anyone would care to explain how the Sunday puzzle can be solved, I'd like to learn more.
GreenLantern
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Post by GreenLantern »

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
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Post by CathyW »

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!
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