Ralph G Selfridge wrote:
> Let me add that the APL finds ALL solutions, no rotations or
> symmetries, and written to print out on a typewriter. Somewhere
> in the code I think I have page width (quad PW), so that as many
> solutions as possible print across the page. Further you get a
> picture of the board, not just coordinate pairs.
> I'll make no attempt to get this to the forum.
> Ralph S
This inspired me to write a verb that creates diagrams from
solution-permutations.
NB. queens coded by Roger Hui; see N-queens essay on the J wiki.
queens=: (, #: I.@,@(</)&i.)~ (] #"1~ [ */@:~:&(|@-/) {)&.|: ! A.&i. ]
$ queens 8
92 8
0 91 { queens 8
0 4 7 5 2 6 1 3
7 3 0 2 5 1 6 4
boards=:' .Q'{~(~:/~8$0 1) >."2 2 (#&0 , 2 , 7&- # 0:)"0 queens 8
$ boards
92 8 8
0 91 { boards
Q. . . .
. . Q .
. . . Q
. . .Q.
.Q. . .
. . . Q
Q . . .
. .Q. .
. . . Q
. .Q. .
Q. . . .
. Q . .
. . Q .
.Q. . .
. . .Q.
. . Q .
This verb does not provide the most interesting features of Ralph's one-liner,
but I happen to not be interested in integrating display and solution into a
single line, nor in maximizing how many diagrams can be printed on a page.
The important thing for me, as an exercise, was doing this without either
boxing or amending.
--
Tracy B. Harms
A good programming language is a conceptual universe
for thinking about programming.
Alan Perlis
____________________________________________________________________________________
You rock. That's why Blockbuster's offering you one month of Blockbuster Total
Access, No Cost.
http://tc.deals.yahoo.com/tc/blockbuster/text5.com
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
