My first Nurikabe puzzle (a difficult one)
Another addition to my portfolio of various number/logic puzzles are Nurikabe puzzles.
I think these puzzles are being undeservedly somewhat neglected in the puzzle world and I intend to change that. The number of solving techniques and approaches that can be found in Nurikabe puzzles far exceeds any other puzzle type. For me it was a challenge programming a solver and a generator of Nurikabe puzzles, much more than programming all other puzzles so far.
Goal:
For each cell, determine if it must be white (draw a circle in it) or black (paint it).
There are two types of Nurikabe jargon:
1) White cells are walls, black cells are a maze.
2) White cells are islands, black cells are a stream.
The Rules of Nurikabe:
1. Cells with numbers (initial clues) are always white.
2. 2×2 (or bigger) blocks of black cells are not allowed.
3. All black cells must be connected orthogonally (horizontally or vertically). In other words: there is a maze between the walls. Or: A stream runs between the islands.
4. The initial numbers (clues) indicate how many white cells are orthogonally connected with the cell that contains the number (including that cell). In other words: the numbers indicate how big each island is; or again, how big each wall is.
5. White cells that “belong” to two different clues must be separated by black cells. In other words: two islands cannot touch each other, there must be some water between them. Or, two walls must be separated by the maze.
6. Nurikabe puzzles can be of any size.
And finally, here is the puzzle. I’m still working on automagically determining the difficulty of these puzzles, but I think this one is quite tough.
Nurikabe 12×12 for July 20, 2009.
Click to download the puzzle in your favorite format:
Folks, I’d really like to hear what you think of Nurikabe puzzles in general and about this particular puzzle (the difficulty in first place). So, please do post your comments!
Killer Sudoku fans
