Hajime wrote:Congratulations Marek, and thanks to mike for the idea of such a nice puzzle.
You're most welcome; I'm glad that it's generated such interest. In case you're wondering how I came up with the idea, it was because of my rather unsuccessful HAPPY NEW YEAR 25x25 sudoku. I failed to generate the 'positive' image that I wanted, but it was trivial to generate a 'negative' one. I then wondered about negative puzzles in general. For 9x9, a negative puzzle would, typically, have 50 or more clues, which isn't very interesting. Then, , if there were to be three puzzles...