Solutions to Race up the Sky – 2/4

Puzzle 3 –  Skyscraper Sudoku
The Sudoku was the first to be made and the last to be completed. I wrote this in April, expecting it to be moderately hard, and at the end of May, when I was test solving, I couldn’t remember my own solving path! I tried adding extra clues to the point that I got very bored and frustrated with my own puzzle. If I, the constructor, got sick of it, then it couldn’t be good for my readers. I scrapped half of my grid and end up with this puzzle.

The solving path is quite narrow, after adding trivial 9s and 8s; you then need to recognize the high skyscrapers clue to restrict your placements.


Now take a look at the first column and the top left region. 3, 4, 5 and 7 are missing and the first column indicates that 4 buildings should be seen. Possible candidates for the C1R2 cell are 4 and 5. 7 can’t be there otherwise you won’t get 4 buildings seen, so 7 will be seen after the 6 and before the 9. You will need to have one more building seen, so if C1R2 is 5, C1R1 cannot obscure the 5 and will see more than 4 buildings. Conclusion: C1R2 is 4.


The next break-in is at the last column. You can see that 6 can only take the C9R6 cell. Staying on the same column, 5 can only be on C9R3 since putting 5 on C9R9 requires a 6 to be seen before the 7 which is impossible.


Even when there were a little more than 10 cells left, the solving still isn’t easy. Every clue and every given had to be used to squeeze out the answer. Lastly, look at C9R9. Filling it with a 3 will have you solving the sudoku for 5 or so more cells to see that it is invalid. You would have to come back and fill C9R9 with a 4 for the puzzle to be completed correctly.


Solutions to Race up the Sky – 1/4

Race up the Sky contained 6 skyscraper variants, here’s a deeper look into each puzzle.
Two quick basic variants to start off Race up the Sky:

Puzzle 1 – Irregular Skyscrapers
The key in Irregular Skyscrapers is in the shapes of the regions. The two weird T’s in the middle and the four regions framing the grid play a crucial role in narrowing the placements of high numbers. You can quickly fill in the 6s and 5s and leave little choice for 4s. The puzzle is quite trivial if you take good notes for all clues. In my view point, this puzzle would be a masterpiece if it wasn’t because of the “4” clue at the top row. But luck isn’t always on a puzzle constructor’s side; otherwise we’d be drowning in beautiful puzzles.

During the 29 days the competition was open, the Indian Puzzle Championship was held. One of the puzzles there was Skyscraper Sudoku, played on a 6×6 irregular grid. The solving path is very similar to this puzzle so those who solved this before the IPC will no doubt blast through the puzzle in seconds.

Puzzle 2 – Skyscrapers with Sum Clues
This variant is credited to Roland’s skyscrapers site. In my original artwork, the four centre cells would sum up to 10, and having the 3×1 cages sum to 11, 12, 13 and 14 would leave you with a very pretty puzzle. In the end, I couldn’t get the 10-clue to work so all you saw was a run of 11, 12, 13 and 14. I thought these cages played out very well with the skyscrapers clue, the high sum narrowed down the number combinations quite conveniently.

Results of Race Up the Sky

The Coit Tower is now closed.
Throughout the 29 days it was opened, 21 people visited the observation deck. Here is the list of entrants in the order of submission:

1. Serkan Yurekli
2. Fatih Kamer Anda
3. Sevgi Sonmez
4. Prasanna Seshadri
5. David Yang
6. Term Ital
7. Maja Gribajcevic
8. Joshua Zucker
9. Ravi Kumar
10. James McGowan
11. Nikola Zivanovic
12. Ivan Koswara
13. Neil Brown
14. Sebastian Matschke
15. Jack Bross
16. Christian Ostermeier
17. Elyot Grant
18. Pierre Billot
19. Scott Handelman
20. Manea Constantin
21. Neil Zussman

At the deck, they were asked arbitrary questions to determine the lucky winner. Each question has two choices; the “correct” answer will be the option that is least selected.

The first question was…
1.         How was your dream last night?
A)         It was a nightmare. I woke up in the middle of night, terrified.
B)         It was so good I didn’t want to wake up.


10 people selected A
11 people selected B
The correct answer is A, 10 people with a nightmare move on to the next question.

2.         What’s for breakfast?
A)         Cereal
B)         Toast


6 people selected A
4 people selected B
The correct answer is B, 4 toast eaters move on to the next question. Although I prefer cereal with fruit.

3.         Is your lucky number…
A)         …an odd number?
B)         …an even number?


1 person selected A
3 people selected B
The correct answer is A

 Congratulations to James McGowan from New Zealand!

He can expect Roland Voigt’s Skyscrapers and Variants arriving in his mailbox soon.
David, Nikola and Scott came pretty close to spoil his victory.

I could not thank you all enough for another great event. Thanks for your participation, interest and the kind feedbacks I’ve received.

Going on this weekend is the 7th Thailand Sudoku Open. I will be reporting results straight from Bangkok here, as the event unfolds.

Here is the PDF for all six puzzles and the solutions will follow in the next few posts.
Planning for my next event is already well underway and I hope you look forward to it as I am.

Stay tuned!