Contact puzzlemix
Play free puzzles         Create free account         Instructions         Discussion forum         Log in    

Show only:

Click on column headings to sort.

Brained Up, daily online brain training site
daily online brain training
Cutting-edge brain training created by Dr Gareth Moore
Think faster, better,
and improve your mental capabilities

Sudoku Xtra, written by Dr Gareth Moore
Sudoku Xtra 24
logic puzzle compendium
Printed puzzles from Dr Gareth Moore


Back to the forum

Comments and Results for 'Skyscraper-6 256'

StateTypeTitleSizePlayedAvg timeRating (#users)YoursYour bestPublishedExpires
UnplayedSkyscraperSkyscraper-6 2566x610310:10Mild (60)Subscribers only5th Oct-
Show full chart rankings for Skyscraper-6 256
Your puzzle statistics First solution time distribution Overall puzzle statistics
Log in (or create a free user)
to store and view your puzzle statistics
Slowest 10% not shown

Solution time without 'show wrong'
Slowest 10% not shown

Unaided first solution time
Slowest 10% not shown
Completed by78 users
Best time without any aid4:23 by tishtosh
Best time with major aid4:19 by purrs
Best time with show wrong
or multiple sessions
0:56 by JoergWausW
Average solve time with no or minor aid9:59
Average solve time with no aid10:13
Average difficulty rating - all players3.7/10.0
Average difficulty rating - no aid3.6/10.0
Average difficulty rating - minor aid5.5/10.0
Average difficulty rating - major aid4.9/10.0
Average difficulty rating - show wrong or
multiple sessions
5 comments (Add new comment)
Posted 11th Oct 2020 at 14:43
Last edited by JoergWausW 11th Oct 2020 at 14:44
JoergWausW Daily subscriber Completion time: 0:56
Ok, I'm stuck here:


So what is the next logical step that I fail to see? Of course I could guess...

Posted 11th Oct 2020 at 20:30
winterer Daily subscriber Rated puzzle: Moderate Best completion time: 5:10 Time on first attempt: 6:53 Used 'show wrong moves' Used 'check puzzle' when incorrect

you need to guess, in order to get a contradiction. Sometimes, it's necessary.

If you set the 4 in the open cell on the left of row 6, you'll have only one cell left in the fourth row to place a 4.
This will force the 3 in column 1, which will lead to a contradiction in row 2.
Hence, the 4 must be placed in the right-hand corner.

Posted 11th Oct 2020 at 21:33
gareth Administrator Daily subscriber Completion time: 31:54 Used 'auto remove' Used 'check puzzle' when incorrect
The puzzle can be solved by some combination of the following:
* Usual sudoku/Latin-square solving techniques up to but not exceeding x-wing
* Evaluating what combination of digits can fit in each square covered by each individual skyscraper clue, given the existing pencil marks, on a separate clue by clue basis (and not simultaneously considering the opposite clue, if present, either)

I know this because the code I use to check the puzzles only has those operations. :)

Posted 11th Oct 2020 at 22:07
gareth Administrator Daily subscriber Completion time: 31:54 Used 'auto remove' Used 'check puzzle' when incorrect
I've run this through my skyscraper solver, and the easiest next step is to eliminate the '4' option from the fourth cell down in the second column. If this was a '4', then it would force the column to have 4 visible skyscrapers instead of 3. This is because placing this 4 would force every other square in the column.

So you can progress by considering only a single skyscraper clue at a time, and while this is not an obvious deduction it is definitely something you can see in your head if you try thinking 'what if this was a 4?' about that cell. :)

After that single deduction, the rest of the puzzle is completely trivial

Posted 11th Oct 2020 at 22:24
JoergWausW Daily subscriber Completion time: 0:56
Thanks to all.

I trusted that you don't have to guess (I can do that, but I don't really want to).
That's why I asked.
I checked "what, if?" most cells in clue-rows and -colums. Starting at the border and with low numbers. But that square in the second column was "hidden" behind the 5 below.

I did this for the 3-clue in the 2nd column:
-> 3 or 4 in bottom row doesn't matter because of the 5.
-> Which one of those two cells has the five? Doesn't matter, because the bottom cell can have the 4.
I even thought this:
-> If the 4th row has a 4, the bottom one is 3 -> the 5 goes directly above(in between) -> no decision possible.
I did NOT see, that this 4 would have more impact in this column.

Thank you!

Add new comment
Add a comment
Your comment:
Sorry: You must log in (create a free user) in order to be able to post comments on this puzzle.

You can however view other players' statistics and comments in the tables above.

Post comment


  • A yellow/light blue highlight in the time distribution charts highlights your time, where relevant.
  • Rating scores out of 10.0 show the average difficulty rating chosen by users, where 1.0 is "Easy" and 10.0 is "Hard".
  • If a puzzle is opened more than once, including by loading from a saved position, then this is potentially a significant aid so it is listed as being completed with 'multiple sessions' for the purpose of the best time/average rating displays above.
  • Minor aid is defined as no more than one use of 'Check solution' when incomplete and/or no more than one use of 'Check solution' when wrong; and/or using highlighting aids (show repeated digits, show broken inequalities and show valid/invalid placements [slitherlink] only). Major aid is any and all other use of the solving aids except for 'show wrong'.

Back to the forum

©Brained Up Ltd/Gareth Moore 2005-2021 - email - publishers please visit Any Puzzle Media - our privacy policy - registered in England & Wales no. 8642393