Dr. Sudoku Prescribes #110 – Skyscrapers (Even/Odd)
or solve online (using our beta test of Penpa-Edit tools)
This is a “Franken-Friday” puzzle variation.
Theme: No givens (this variation was inspired in part by the Even/Odd round at the 19th WPC by Lukasz Bozykowski.)
Rules: Standard Skyscrapers rules. All even digits (and only even digits) have been shaded gray. Note: this means that all unshaded digits, including unshaded outside digits, are odd.
Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 3rd row from left to right.
Time Standards (highlight to view): Grandmaster = 2:45, Master = 4:00, Expert = 8:00
Solution: PDF
The title of the pdf says 135024-Battleship-Mines – 130607-Skyscrapper-EO.pdf. Is that a typo, or is there some significance to it?
Doesn’t open that way for me in Preview, but I suspect it must be some old meta-data from the Illustrator file I was using when building the grid. Not a part of any hidden contest or something to worry about.
04:56. I should have expected that the last 20ish digits are pure Latin squares; usual in these Even-Odd things 😛
Great puzzle. Takes a minute or two to discover new deductions that can be made from this type (Even-Odd) of puzzles, and new deductions are always nice. 😀
Loved this puzzle. Flowed nicely, and very much enjoyed the new discoveries that chaotic_iak noted. Not too good of a score (8:47), but I’m the snail around here … just happy to be moving forward dropping slime along the way at my old age.
Ken
You should probably specify that the answer string only requires the digits inside the square.
While this is an implicit part of the entry for this puzzle type in normal circumstances, I must admit I wondered if someone would have this problem with this unusual format where no outside skyscraper digits are given but the solver seems to be solving for them during the puzzle. So your comment did bring a smile to my face. I hope that is apology enough for any confusion you had.
Yeah, I was 99% sure that you meant only the digits inside the grid, but the thought lingered in my head as well as I was entering.
Yeah, I’m no professional solver– I rarely come in under even the expert time– so all the “inside baseball” rules are foreign to me.
Same thing happens on the Nurikabe puzzles. I’m constantly listing my values for the white squares in each row first. (Or is the black squares? Either way, my first guess is wrong pretty much every time!)
Right. I added extra language on the Nurikabe to say it is the black cells or “the unnumbered, connected ocean” but the first is inaccurate for at least some solvers who like to shade in the islands and not the ocean. I think the Masyu entry is the most error-prone though.
That was beautiful! Lots of time at the beginning figuring out what kinds of things can be deduced from even/odd clues around the outside, and then some other nice logic in the middle, and then a very fast and easy ending. Almost all the time is spent thinking through the beautiful logic of this type of puzzle.
I think figuring out where the 5s go was the most fun part.
It looks like if one interprets the rules to say that the shaded outside numbers must be even, but the unshaded outside numbers can be either even or odd, then two solutions are possible.
This may be a reasonable interpretation since most skyscrapers puzzles don’t show all the outside numbers, and some solvers (like myself!) may not bother filling in the unshaded outside numbers, thinking that they’re not part of the puzzle.
My use of the word “all” meant all, including all potential outside digits. But I’ve added a note to remove this potential confusion.
Thanks! Love your puzzles by the way (and Grant’s!). I’m mainly a fan of the non-latin-square ones, so it’s too bad that MellowMelon’s blog has been on indefinite hiatus. Also, hex cell variants are great! (:
I don’t know if my deductions are new, but I used a lot like “this even clue must be 2 or 4, so the 2nd (odd) cell after the clue must be 1 or 3”.
Loved it !
This was really fun, even though it wasn’t that hard. I didn’t time myself but I’d guess it took around 3-4 min.
Did anyone else get the answer rows finished before the entire puzzle?
I did — which is unusual on this site, admittedly, but filling in the remaining rows was fairly trivial from that point, anyway.
10:27 .Very slow start and a very quick end to this puzzle.