good chemistry is complicated, and a little bit messy LW 

PerlMonks 
Comment on 
( #3333=superdoc: print w/ replies, xml )  Need Help?? 
For (e.g., for $N = 11: [ a1, b3, c5, d7, e9, f11, g2, h4, i6, j8, k10 ]) This is equivalent to starting in the bottomleft corner of the board and moving right one square and up two squares (wrapping when you hit the edge) N1 times. If the regex picks the first space notalreadycapturable in each column (From brief inspection, it appears to do so  It finds an equivalent solution for oddN), this is the first solution it will find. In the evenN case, this process will not leave any notalreadycapturable squares in the last column on the first pass, so it must then backtrack. Update: Whoa there, Ben. I spoke way too soon. The above solution only applies when N is odd AND not divisible by 3. (So, for N = (1,5) mod 6) More update: I was wrong about most of the analysis, too. This won't be the first solution found. In reply to Re: Re: Re: The Nqueens problem using pure regexes
by benizi

