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ZeroAssoluto
Joined: 05 Feb 2017 Posts: 942 Location: Rimini, Italy
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Posted: Mon Jun 28, 2021 7:32 am Post subject: Jun 28 VH |
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Hi everyone,
Code: |
+--------------+------------+------------+
| 269 1 49 | 8 39 3469 | 7 29 5 |
| 7 234 489 | 1 5 49 | 238 6 234 |
| 69 345 4589 | 2 7 469 | 1 89 34 |
+--------------+------------+------------+
| 8 45 459 | 39 2 1 | 6 35 7 |
| 3 6 1 | 7 4 5 | 28 28 9 |
| 29 25 7 | 6 8 39 | 4 35 1 |
+--------------+------------+------------+
| 4 7 2 | 5 39 8 | 39 1 6 |
| 1 9 3 | 4 6 2 | 5 7 8 |
| 5 8 6 | 39 1 7 | 239 4 23 |
+--------------+------------+------------+
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Play this puzzle online at the Daily Sudoku site
Quote: | Skyscraper with number 9 in r2c36,r6c16 and -9 in r13c1,r4c3
or
Skyscraper with number 9 in r2c36,r4c34 and -9 in r6c6 |
Ciao Gianni |
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TomC
Joined: 30 Oct 2020 Posts: 358 Location: Wales
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Posted: Mon Jun 28, 2021 9:41 am Post subject: |
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r1c6 <> 3 as then r1c1=6, r3c1=9, r1c5=9 leading to no 9's in box 3 |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Mon Jun 28, 2021 5:23 pm Post subject: |
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Glory be! A fish. It is a swordfish for 9s in r136c16 r13c8
This swordfish has a fin at r2c6. It doesn't matter because whether the swordfish is true or the fin is true, the 9 in r1c5 is toast. |
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peter urhegyi
Joined: 26 Oct 2020 Posts: 28
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Posted: Tue Jun 29, 2021 7:37 am Post subject: Daily sudoku Jun 28 VH |
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In case anyone will try the classical solution with only xy(z) wings requires 2 xyz-wings and 2 xy-wings that are all necessary to solve. |
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Mogulmeister
Joined: 03 May 2007 Posts: 1151
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Posted: Tue Jun 29, 2021 10:29 am Post subject: |
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Hi Peter - yes a v good point which is why (imho) wings are helpful but also should be augmented with different ways of looking at strong links.
This puzzle is great because it shows good examples of great alternatives to the classical approach if you take different looks at strong links - sometimes with more efficient solutions:
Pattern
1)Gianni's skyscrapers - the strong links on 9's in r24. They share a base in c3 so either r4c4 is 9 or r2c6 is 9 and r6c6 is <>9.
2)Finned swordfish for 9's and r1c5 <> 9
Observation/Inspection
3)TomC disrupting the strong link on 6's in r1. A 3 in r1c6 makes r1c5 a 9 and also makes r3c1 a 9 which means no 9's in box 3 = impossibility - so it is eliminated. Solved. That 3 in r1c6 is also part of a strong link with r6c6. |
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dongrave
Joined: 06 Mar 2014 Posts: 568
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Posted: Tue Jun 29, 2021 12:41 pm Post subject: Re: Daily sudoku Jun 28 VH |
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peter urhegyi wrote: | In case anyone will try the classical solution with only xy(z) wings requires 2 xyz-wings and 2 xy-wings that are all necessary to solve. |
That's how I solved it peter! (I wasn't sure if they were all necessary though.) I started with a 269 XYZ Wing (pivot at r1c1, -9r1c3), then a 234 XYZ Wing (pivot at r2c9, -3r2c7), then a 28-9 XY Wing (pivot at r2c7, -9r1c1), and finally a 26-9 XY Wing (pivot at r1c1, -9r3c8). |
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