Kuromasu (Double) by Prasanna Seshadri
or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)
Theme: Clue Symmetry and Logic
Author/Opus: This is the 43rd puzzle from our contributing puzzlemaster Prasanna Seshadri.
Rules: Shade some dominoes (pairs of empty cells) black so that each number indicates the total count of white cells connected vertically and horizontally to that number including the numbered cell itself. Dominoes cannot share an edge, and all white cells must belong to a single connected group. Or see this example:
Answer String: Enter the length in cells of each of the white segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma. This example has the key “23,15”.
Time Standards (highlight to view): Grandmaster = 6:45, Master = 9:00, Expert = 18:00
Solution: PDF
Note: Kuromasu is a new puzzle for us this week and we are curious to hear what you think of it.
03:15.
Obviously due to a lucky guess at the opening (although apparently the contradiction for the other guess is rather quick). A great one with many components acting together nicely. Well done.
I really like the way the two 2s in the middle interact with each other.
– Neelix
14:57