Theme: Sudoku GP Round 7, plus two hidden themes related to 7
(Note: this puzzle was originally created for the Sudoku Grand Prix but after testing was judged too hard and too puzzle-based for the competition. It is an excellent puzzle, and we are proud to showcase it here.)
Author/Opus: This is the 40th puzzle from our contributing puzzlemaster Prasanna Seshadri.
Rules: Standard Sudoku rules. Also, standard Skyscrapers rules. Additionally, the cells in grey are “underground” and cannot be seen by any of the outside skyscraper clues (think of them as starting with a negative sign if necessary). As an example, the 3 on the left of row 2 refers only to seeing three buildings in columns 2 through 9, even if there is a 9 in column 1 as that 9 cannot be seen.
Answer String: Enter the 1st row from left to right, followed by a comma, followed by the 5th row from left to right.
Time Standards (highlight to view): Grandmaster = 7:00, Master = 10:00, Expert = 20:00
Note: Follow this link for our first Basement Skyscraper Sudoku. Follow this link for other less common variations of Sudoku and this link for classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on.