Daniel Doubrovkine bio photo

Daniel Doubrovkine

aka dB., CTO at artsy.net, fun at playplay.io, NYC

Email Twitter LinkedIn Github

The eight queens puzzle is the problem of putting eight chess queens on an 8×8 chessboard such that none of them is able to capture any other using the standard chess queen’s moves. The queens must be placed in such a way that no two queens would be able to attack each other. Thus, a solution requires that no two queens share the same row, column, or diagonal. The eight queens puzzle is an example of the more general n queens puzzle of placing n queens on an n×n chessboard, where solutions exist only for n = 1 or n ≥ 4.


I dug up some old code that implemented the puzzle solution(s) in scheme and x86 assembly.

I remember trying to get solutions for large (over 10) boards in 1995 and my PC was a little slow. Things are very different today. Here’s an example of solution number 128570 for a board of 20.

(128570) 11 1 3 5 12 2 15 13 18 14 4 6 19 16 10 7 20 8 17 9