[Korrelan]

http://www.gizmodo.co.uk/2017/09/why-computers-are-having-such-a-hard-time-with-this-deceptively-simple-chess-puzzle/

 

[Freddy]

When I was about 5 or 6 we had this chess board at my grandparents and my Dad told me about this puzzle and explained what I had to do but not how to do it. Dad left me to it, to be quiet for a while.

So there I was with a few draughts pieces and I cleverly noticed there were very small faint crosses marked on the old chess board at certain places.

Something in my mind made me think to place the pieces on the squares marked with the crosses. And so a few moments later I called Dad over and asked if I got it right. He contained himself very well and said yes, he was surprised. Then I revealed what I had done and there was a wry smile.

[infurl]

Solving the 8 Queens puzzle was a CS100 first year programming assignment at university. It's very simple using recursive programming, I think it was the second programming assignment that we were given. For an 8x8 board it can't have taken too much processing time. The university had just spent a million dollars on a new VAX computer with a whopping 2MB of RAM.

A much more interesting puzzle I thought was Pentominoes which I first read about in Arthur C. Clarke's novel "Imperial Earth". I always vowed that one day I would solve it and a few years ago I did just that. It took my work station about half an hour to find all the solutions to the standard 6x10 puzzle.

@Freddy excellent solution