I used a web site to help solve a square that I was stuck with:
609240007
002076090
173090624
806430079
090000060
000069005
918000746
000687912
267914358
When it got to where I was stuck, it found:
HIDDEN UNIQUE RECTANGLE Type 2: removing 5 at E4 because of CE46 and one strong link between C6 and E6
Trouble is - I still don't see it.
Could someone explain this in more detail for me to understand it?
Thanks
Not seeing hidden unique rectangle
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- Location: Colorado
Howard, almost no one visits these forums anymore. I suggest you repost your question at the forums that were set up to replace these:
http://www.rcbroughton.co.uk/sudoku/forum/index.php
http://www.rcbroughton.co.uk/sudoku/forum/index.php
Re: Not seeing hidden unique rectangle
Sure, I can possibly explain but the suggestion wasn't great as that removal doesn't help much.HowardBrazee wrote:I used a web site to help solve a square that I was stuck with:
609240007
002076090
173090624
806430079
090000060
000069005
918000746
000687912
267914358
When it got to where I was stuck, it found:
HIDDEN UNIQUE RECTANGLE Type 2: removing 5 at E4 because of CE46 and one strong link between C6 and E6
Trouble is - I still don't see it.
Could someone explain this in more detail for me to understand it?
Thanks
There are 2 valid hidden rectangles on 5 in this position. The one you ask about is this.
Code: Select all
.------------------.------------------.------------------.
| 6 58 9 | 2 4 13 | 158 38 7 |
| 45 458 2 | 13 7 6 | 58 9 13 |
| 1 7 3 |*58 9 *58 | 6 2 4 |
:------------------+------------------+------------------:
| 8 25 6 | 4 3 125 | 12 7 9 |
| 3457 9 145 |*178-5 25 *1258 | 1248 6 13 |
| 347 234 14 | 178 6 9 | 1248 38 5 |
:------------------+------------------+------------------:
| 9 1 8 | 35 25 235 | 7 4 6 |
| 345 345 45 | 6 8 7 | 9 1 2 |
| 2 6 7 | 9 1 4 | 3 5 8 |
'------------------'------------------'------------------'
If r5c4 is 5 then you get this deadly pattern:
Code: Select all
.------------------.------------------.------------------.
| 6 58 9 | 2 4 13 | 158 38 7 |
| 45 458 2 | 13 7 6 | 58 9 13 |
| 1 7 3 |*8 9 *5 | 6 2 4 |
:------------------+------------------+------------------:
| 8 25 6 | 4 3 125 | 12 7 9 |
| 3457 9 145 |*5 25 *8 | 1248 6 13 |
| 347 234 14 | 178 6 9 | 1248 38 5 |
:------------------+------------------+------------------:
| 9 1 8 | 35 25 235 | 7 4 6 |
| 345 345 45 | 6 8 7 | 9 1 2 |
| 2 6 7 | 9 1 4 | 3 5 8 |
'------------------'------------------'------------------'
Here is the other hidden rectangle, this one on 25 rather than 58.
Code: Select all
.------------------.------------------.------------------.
| 6 58 9 | 2 4 13 | 158 38 7 |
| 45 458 2 | 13 7 6 | 58 9 13 |
| 1 7 3 | 58 9 58 | 6 2 4 |
:------------------+------------------+------------------:
| 8 25 6 | 4 3 125 | 12 7 9 |
| 3457 9 145 | 1578 *25 *128-5| 1248 6 13 |
| 347 234 14 | 178 6 9 | 1248 38 5 |
:------------------+------------------+------------------:
| 9 1 8 | 35 *25 *235 | 7 4 6 |
| 345 345 45 | 6 8 7 | 9 1 2 |
| 2 6 7 | 9 1 4 | 3 5 8 |
'------------------'------------------'------------------'
Code: Select all
To actually solve the puzzle I suggest these 2 steps rather than the hidden URs.
First an x-wing on 1s.
.------------------.------------------.------------------.
| 6 58 9 | 2 4 *13 |*158 38 7 |
| 45 458 2 | 13 7 6 | 58 9 13 |
| 1 7 3 | 58 9 58 | 6 2 4 |
:------------------+------------------+------------------:
| 8 25 6 | 4 3 *125 |*12 7 9 |
| 3457 9 145 | 1578 25 258-1| 248-1 6 13 |
| 347 234 14 | 178 6 9 | 248-1 38 5 |
:------------------+------------------+------------------:
| 9 1 8 | 35 25 235 | 7 4 6 |
| 345 345 45 | 6 8 7 | 9 1 2 |
| 2 6 7 | 9 1 4 | 3 5 8 |
'------------------'------------------'------------------'
Then an xyz-wing on 258.
.------------------.------------------.------------------.
| 6 58 9 | 2 4 13 | 158 38 7 |
| 45 458 2 | 13 7 6 | 58 9 13 |
| 1 7 3 | 58 9 *58 | 6 2 4 |
:------------------+------------------+------------------:
| 8 25 6 | 4 3 12-5 | 12 7 9 |
| 3457 9 145 | 1578 *25 *258 | 248 6 13 |
| 347 234 14 | 178 6 9 | 248 38 5 |
:------------------+------------------+------------------:
| 9 1 8 | 35 25 235 | 7 4 6 |
| 345 345 45 | 6 8 7 | 9 1 2 |
| 2 6 7 | 9 1 4 | 3 5 8 |
'------------------'------------------'------------------'
The rest is clean-up!