## Skyscraper sudoku help

For fans of Killer Sudoku, Samurai Sudoku and other variants

### Skyscraper sudoku help

Hello everyone,
I've been toying around with two sudoku puzzles for a while now, and keep getting stuck. These are special types, both pertaining to the Skyscraper puzzle, where the numbers at the beginning and end of each row and column indicate how many "buildings" can be seen from that side. For example, if you have 156 in a row, that means you can see all three, but if you have 516, you only see two. The harder one of these two puzzles has the sum of the height of seen buildings indicated. I would appreciate any help in solving these two, because right now, I'm getting nowhere fast. Thanks in advance!

https://s3.amazonaws.com/gs-geo-images/5e9a29ba-094f-4723-bbf6-676c17cf72ee_l.jpg
https://s3.amazonaws.com/gs-geo-images/c05455a2-90e2-481a-912c-8c18a1c62531_l.jpg
gabor316

Posts: 1
Joined: 09 March 2017

### Re: Skyscraper sudoku help

For the second puzzle, I'd suggest that column 7 offers a start, since 10 can only result from a 1 in (1,7) and a 9 in (2,7).

From the other end, 37 requires at least 6 buildings visible.

I'd suggest generating a file of the 362880 permutations available, the skyscraper values at each end, plus the building totals would be a useful thing to have. Then make a lookup function to tell you what limited possibilities can possibly make extreme case like col 7.

BTW, what are those "A","B","C" labels signifying?
Last edited by Mathimagics on Fri Mar 10, 2017 4:15 pm, edited 1 time in total.

Mathimagics
2017 Supporter

Posts: 760
Joined: 27 May 2015

### Re: Skyscraper sudoku help

SudoKai v4 can not be much help since this is part of my Sudoku Kryptonite which I still need to conquer.

But you could look at the following for some solving techniques:
http://www.conceptispuzzles.com/index.aspx?uri=puzzle/skyscrapers/techniques

As for the 'sum of the height', I would suggest you treat this as a Killer Sudoku, or to be more correct - a Twin Killer variant.
SudoKai

Posts: 30
Joined: 07 June 2014
Location: South-Africa

### Re: Skyscraper sudoku help

This is the first time I have seen the sum variant of Skyscrapers.

It is essentially an ordered uncaged killer. Twin killer is appropriate as I always make non-standard cages as twins in JSudoku.

I enjoyed it (not too difficult, not much combination work) and will probably create some on the Assassin site.

Gabor where did these come from?

On terminology I suggest "slum cell" for those cells hidden in all directions by skyscrapers, which must be solved by pure sudoku techniques.

This is the same puzzle with a few redundant clues removed.

HATMAN

Posts: 214
Joined: 25 February 2006