Nanro (Triangle) by Martin Ender, inspired by “Composition with Grid 4: Lozenge Composition” by Piet Mondrian
[Editor’s Note / context: For those looking for more puzzles here besides Sudoku, we still don’t have new plans for this year. We need more focus on the large efforts we have underway and in general that still means on Sudoku and staying healthy until we can grow the team. But as editors, we too miss the unexpected submissions that surprise and delight.]
[Now you can’t just commission a “museum series” of unforgettable grids, but we were delighted by what happened here. A few months ago Thomas shared a photo (far below) he takes every time he visits the Philadelphia Museum of Art, thinking this grid by Mondrian will always deserve a puzzle when he can get to it. Without expectation of anything appearing, Martin delivered a tremendous fit for the grid, that used its elements fully, that added its own theme with just three kinds of givens that left us a bit shocked. We’re pleased to share now as a bonus for all to enjoy.]
or solve online (using our beta test of Penpa-Edit tools; use the tab key to alternate between shading and number entry modes)
Author/Opus: This is the 18th puzzle from guest contributor Martin Ender.
Rules: Label some cells with numbers to form a single connected group of labeled cells; no gridpoint is entirely surrounded by numbered cells. Each bold region must contain at least one labeled cell. Each number (including any given numbers) must equal the total count of labeled cells in that region. Two cells containing the same number may not share a thick border.
Difficulty: 4 stars
Time Standards (highlight to view): Grandmaster = 10:00, Master = 25:00, Expert = 50:00
Solution: PDF and solving animation.
Note: Follow this link for Nanro puzzles on this website and this link for variations on Nanro puzzles. If you are new to this puzzle type, here are our easiest Nanro Puzzles to get started on. More Nanro puzzles can be found in A Number o’ Nanro by Prasanna Seshadri.
Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our General Blog Puzzle Discussion on the GMPuzzles Discord.
I assume there is a small error in the grid : shouldn’t the thick border below the given 5 in “row” 2 be a thin line ?
I see that the original Mondriaan grid also has that border but as a puzzle that line confuses me…
The author has followed the artist here. If you read the instructions, one of the Nanro rules is stated this way: “Two cells containing the same number may not share a thick border.” This region versus bold line framing is similar to how some Heyawake are made these days too.
Thanx for the answer Thomas.
I guess I find it confusing that not all thick lines must be regions borders.