Thursday, 24 May 2012

Puzzle #108: Not Alone

While creating the Black and White Matchmaker as a practise puzzle, I discovered an interesting logic deduction regarding the "Not Alone" puzzle type, which I thought could lead to an interesting puzzle and severely reduce the amount of clues necessary to make it unique. So I tried it and brought it down to only 10 clues. I'm not convinced this is the minimum, but it's far fewer than I thought at first. At first the puzzle reminded me of the Binary puzzles, which are now also published here in a seperate booklet, which I find a boring puzzle type. But this rule is actually far more interesting that those puzzles. This one was pretty fun to create. I wonder how it will be perceived as difficulty. If you realise the one logic deduction I exploited here, it shouldn't be too hard. When you don't realise it, I don't know how people will feel about it.


Fill the grid with black or white circles so that each row or column has the same amount of black circles and white circles. One circle of a color can't be sandwiched by circles of the other color horizontally or vertically.
An array of two or more circles of a same color may be sandwiched by circles of the other color  horizontally or vertically.


  1. I have a feeling I didn't realize that one logic deduction you made... At least I didn't explicitly reuse the deduction that helped me break in (spoiler: fourth row) . After that it flowed pretty easily.

    1. That's the right deduction. Initially there were a few more places it came back, but having to make it unique with the three clues on the outer edge, some of the places could be avoided. In the Black and White Matchmaker you can find a few places where the circle placements break the deduction made in row 4.