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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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 Posted: Fri Apr 04, 2008 5:18 am Post subject: competition #999... plus extra |
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from sudokulist...this is number 999... so I am wondering if this is the last competition puzzle in which Ravel will attempt to solve... I fear the worst if Ravel attempts #1000.
| Code: | 1 . 2 | . . . | . . 3
. 6 . | . . 9 | . . .
5 . . | 7 . . | . . 8
- - - + - - - + - - -
4 1 . | . 3 . | . 8 .
. . . | . 4 . | . . .
. 3 . | 9 7 . | . 2 1
- - - + - - - + - - -
6 . . | . . 7 | . . 4
. . . | 8 . . | . 3 .
2 . . | . . . | 9 . 7 |
-------
extra puzzles
this puzzle provides an interesting pattern on the numbers 9 and 6, just thought it was interesting to see.
| Code: | . . . | 7 3 . | . . 1
. . . | . . . | 2 . .
. 2 . | 6 . 9 | . . 8
- - - + - - - + - - -
. 5 4 | . . . | 9 . .
. . 1 | . 2 . | 6 . .
. . 3 | . . . | 7 8 .
- - - + - - - + - - -
5 . . | 2 . 1 | . 4 .
. . 7 | . . . | . . .
8 . . | . 5 3 | . . . |
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much like the very long winding path of a puzzle that Victor posted, this one has a few hills and streams to cross.
| Code: | . 3 . | 6 . . | 7 . .
5 . . | 3 . . | . . 8
. . 8 | . 9 5 | . . 6
- - - + - - - + - - -
. . 5 | . 8 6 | . . 9
. . . | . . . | . . .
6 . . | 1 7 . | 4 . .
- - - + - - - + - - -
1 . . | 9 4 . | 8 . .
2 . . | . . 3 | . . 1
. . 9 | . . 1 | . 2 . |
enjoy, |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Fri Apr 04, 2008 7:09 pm Post subject: |
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Nice bunch of puzzles, S_N. First one is easy (if you like remote pairs, which is all it takes).
2nd one. Didn't see any fancy moves with 6s & 9s unfortunately, but still liked it. Solved with (a) XY-wing, extended, (b) an ER, (c) a finned X-wing, and finished off with (d) BUG + 1.
3rd. After basics & several UR eliminations:
| Code: |
+---------------+---------+--------------+
| 49 3 124 | 6 12 8 | 7 1459 45 |
| 5 12469 246 | 3 12 7 | 129 149 8 |
| 7 12 8 | 4 9 5 | 123 13 6 |
+---------------+---------+--------------+
| 34 147 5 | 2 8 6 | 13 17 9 |
| 89 12789 127 | 5 3 4 | 6 178 27 |
| 6 28 23 | 1 7 9 | 4 358 235 |
+---------------+---------+--------------+
| 1 5 367 | 9 4 2 | 8 367 37 |
| 2 4678 467 | 78 56 3 | 59 4679 1 |
| 348 468 9 | 78 56 1 | 35 2 347 |
+---------------+---------+--------------+
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Probably somebody can spot something smart with 13s or otherwise, but I needed lots of XY-chains - a long path as you say. I liked the first few I found, because they're all to do with the same box, no.4. E.g. note the nice fact that if you start with 28 in r6c2 & run up & down c1, you end with the 23 beside it: so we can eliminate other 2s in box 4 or r6. |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Fri Apr 04, 2008 10:22 pm Post subject: |
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| PS. It's no big deal, but attractive, that the reason why you can do three eliminations based round box 4 & c1 is that the 5 cells form an XY-loop: 49,98,82,23,34 & back to 49. One of each pair of successive numbers must be true, and so you can eliminate any other appearance of that number from the house in which they appear. That means any other 4s (or 9s if there were any) in c1, any other 8s in box 4 (or 3s if there were any) and other 2s in box 4 & r6. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Fri Apr 04, 2008 11:19 pm Post subject: |
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The 3rd one kept me busy for some time, first there is a @finned x-wing on <3> which eliminates <3> in R7C8, followed by a {56}* UR deleting both <6>'s in R89C7(x-wing <5> in UR, placing <6> in R89C7=56DP)
| Code: | +-------------------------+-------------------------+-------------------------+
| 49 3 124 | 6 12 8 | 7 1459 245 |
| 5 12469 1246 | 3 12 7 | 129 149 8 |
| 7 12 8 | 4 9 5 | 123 13 6 |
+-------------------------+-------------------------+-------------------------+
| 34 147 5 | 2 8 6 | 13 137 9 |
| 89 12789 127 | 5 3 4 | 126 1678 27 |
| 6 28 @ 23 | 1 7 9 | 4 358 @ 235 |
+-------------------------+-------------------------+-------------------------+
| 1 5 @ 367 | 9 4 2 | 8 -[3]67 @ 37 |
| 2 4678 467 | 78 *56 3 |*5-[6]9 4679 1 |
| 348 4678 9 | 78 *56 1 |*35-[6] 2 F 347 |
+-------------------------+-------------------------+-------------------------+
|
Then a 5-cell xy-chain {23-34-49-98-82} with pincer ends at R6C3(A) and R6C2(E) eliminating <2> in R5C23 and R6C9
| Code: | +-------------------------+-------------------------+-------------------------+
| 49 C 3 124 | 6 12 8 | 7 1459 45 |
| 5 12469 1246 | 3 12 7 | 129 149 8 |
| 7 12 8 | 4 9 5 | 123 13 6 |
+-------------------------+-------------------------+-------------------------+
| 34 B 147 5 | 2 8 6 | 13 137 9 |
| 89 D 1-2789 1-27 | 5 3 4 | 6 178 27 |
| 6 E 28 23 A | 1 7 9 | 4 358 -235 |
+-------------------------+-------------------------+-------------------------+
| 1 5 367 | 9 4 2 | 8 67 37 |
| 2 4678 467 | 78 56 3 | 59 4679 1 |
| 348 4678 9 | 78 56 1 | 35 2 347 |
+-------------------------+-------------------------+-------------------------+ |
Finally Medusa coloring starting with the {56} pair in Box 8 traps the <9> in R1C8(the uncolored <9> in R1C8 can see 9G while the opposite color R is in its own cell.)
| Code: | +-------------------------+-------------------------+-------------------------+
| 49 3 124 | 6 12 8 | 7 145R-[9] 4R5G |
| 5 12469 1246 | 3 12 7 | 129G 149 8 |
| 7 12 8 | 4 9 5 | 123 13 6 |
+-------------------------+-------------------------+-------------------------+
| 34 147 5 | 2 8 6 | 13 137 9 |
| 89 1789 17 | 5 3 4 | 6 178 2 |
| 6 28 23 | 1 7 9 | 4 358 3G5R |
+-------------------------+-------------------------+-------------------------+
| 1 5 367 | 9 4 2 | 8 6 37 |
| 2 4678 467 | 78 5R6G 3 | 5G9R 4R9G 1 |
| 348 46G78 9 | 78 5G6R 1 | 3G5R 2 34G7 |
+-------------------------+-------------------------+-------------------------+ |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Sat Apr 05, 2008 7:50 pm Post subject: |
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Since Johans xy-chain is also a loop (r5c2=3 => r5c3=3), you also can eliminate the 4 in r9c1 and the 8 in r5c2.
Also there is a rather useless w-wing 12 in r2c5 and r3c2, strong link for 2 in row 1, which kills 1 in r2c23.
| Code: | *------------------------------------------------------------*
|#49 3 12-4 | 6 12 8 | 7 1-459 #45 |
| 5 2469 246 | 3 12 7 | 129 149 8 |
| 7 12 8 | 4 9 5 | 123 13 6 |
|-------------------+-------------------+--------------------|
| 34 147 5 | 2 8 6 | 13 137 9 |
|#89 179 17 | 5 3 4 | 6 178 2 |
| 6 #28 #23 | 1 7 9 | 4 -358 #35 |
|-------------------+-------------------+--------------------|
| 1 5 37 | 9 4 2 | 8 6 37 |
| 2 4678 467 | 78 56 3 | 59 49 1 |
| 38 4678 9 | 78 56 1 | 35 2 347 |
*------------------------------------------------------------*
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Here another xy-chain, which forms a loop, solves the puzzle. It starts at r1c1 and ends in r1c9. (The loop eliminations are, as often, weak and not needed, r1c38<>4 already solves the puzzle with an xy-wing) |
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