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peter urhegyi
Joined: 26 Oct 2020 Posts: 28
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Posted: Sat Apr 01, 2023 9:53 am Post subject: 01-04-2023-vh+ |
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Code: |
+-------+-------+-------+
| 9 . . | . 2 . | . . . |
| . 1 . | . . . | . 6 . |
| . . 2 | 7 . . | . . 4 |
+-------+-------+-------+
| . . 1 | . . . | 9 . . |
| . . . | . 4 . | . . 5 |
| . 5 . | 6 . . | . 7 . |
+-------+-------+-------+
| . 4 . | . 5 . | 8 . . |
| . . 7 | . . 9 | . 2 . |
| 6 . . | 1 . . | . . . |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site |
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dongrave
Joined: 06 Mar 2014 Posts: 568
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Posted: Sat Apr 01, 2023 8:48 pm Post subject: |
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Wow! This was a tough one! You know how many cells I solved using basics? None!
I couldn't find a single step solution so I used 2 steps.
After basics: Code: | +------------------------+--------------------+--------------------+
| 9 3678 34568 | 3458 2 134568 | 1357 1358 1378 |
| 34578 1 3458 | 34589 389 3458 | 2357 6 23789 |
| 358 368 2 | 7 13689 13568 | 135 13589 4 |
+------------------------+--------------------+--------------------+
| 23478 23678 1 | 2358 378 23578 | 9 348 2368 |
| 2378 236789 3689 | 2389 4 12378 | 1236 138 5 |
| 2348 5 3489 | 6 1389 1238 | 1234 7 1238 |
+------------------------+--------------------+--------------------+
| d123 4 b39 | 23 5 67 | 8 c139 67 |
| 1358 38 7 | 348 368 9 | 13456 2 136 |
| 6 ae2389 3589 | 1 378 23478 | 3457 3459 379 |
+------------------------+--------------------+--------------------+ |
Step 1: 9r9c2-r7c3=(9-1)r7c8=(1-2)r7c1=r9c2 contradiction (i.e. 9r9c2, 2r9c2).
Code: | +-----------------+--------------+-------------+
| 9 7 6 | 345 2 345 | 1 58 38 |
| 345 1 345 | 9 38 358 | 2 6 7 |
| 358 38 2 | 7 1 6 | 35 9 4 |
+-----------------+--------------+-------------+
| 2348 6 1 | c358 7 c358 | 9 d48 238 |
| 7 9 a38* | b38 4 2 | 6 1 5 |
| 2348 5 348 | 6 9 1 | 34 7 238 |
+-----------------+--------------+-------------+
| 1 4 9 | 2 5 7 | 8 3 6 |
| g358 g38 7 | h348 6 9 | 45 2 1 |
| 6 2 f358 | 1 38 348 | 7 e45 9 |
+-----------------+--------------+-------------+ |
Step 2: 8*r5c3-(8=3)r5c4-(3=5|8)r4c46-(8=4)r4c8-(4=5)r9c8-(58*=3)r9c3-r8c12=r8c4 contradiction (i.e. 3r58c4) => r5c3 <> 8; stte. |
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glesco
Joined: 12 May 2022 Posts: 36
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Posted: Sun Apr 02, 2023 8:13 pm Post subject: |
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Excellent puzzle! Didn't solve; going to try again.
Please post more if you have any! |
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 9:47 pm Post subject: |
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Ahhh. The rarely identified and and even more rarely used (by me) Swordfish pattern. It is in there; albeit near impossible to locate. And that is only my first step.
Swordfish: (9) r367 c358 => r2c5,r59c3,r9c8<>9. |
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 9:57 pm Post subject: |
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This reveals a Naked Triple in c5 of (378). Followed by many singles (hidden and naked), Locked candidates (pointing), and a Naked and Hidden Pair. Then some more singles. |
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 10:10 pm Post subject: |
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That brings me here:
Code: |
+-------------+------------+-----------+
| 9 7 6 | 345 2 345 | 1 58 38 |
| 345 1 345 | 9 38 358 | 2 6 7 |
| 358 38 2 | 7 1 6 | 35 9 4 |
+-------------+------------+-----------+
| 2348 6 1 | 358 7 358 | 9 48 238 |
| 7 9 38 | 38 4 2 | 6 1 5 |
| 2348 5 348 | 6 9 1 | 34 7 238 |
+-------------+------------+-----------+
| 1 4 9 | 2 5 7 | 8 3 6 |
| 358 38 7 | 348 6 9 | 45 2 1 |
| 6 2 358 | 1 38 348 | 7 45 9 |
+-------------+------------+-----------+
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 10:12 pm Post subject: |
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Used an X-Wing: (5) r38 c17 => r2c1<>5. |
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 10:17 pm Post subject: |
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Now an Empty Rectangle: (3) in b7 (r5c34) => r8c4<>3. Followed by Locked candidates (3) pointing in box 8. |
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 10:20 pm Post subject: |
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And my last Empty Rectangle: (8) in b7 (r5c34) => r8c4<>8. stte |
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immpy
Joined: 06 May 2017 Posts: 571
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Posted: Tue Apr 04, 2023 10:23 pm Post subject: |
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Whew! That was indeed a very tough puzzle. Thank you Peter for submitting it.
cheers...immp |
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