Lisp(y) A* search implementation

[AceKnocks]

Thanks Jos for that encouragement. :)

Let's see if you really allowed your Lisp(y) knowledge to fade away in midst of those C's and Java's.. Here goes,

If we have following array

(setf *possible-die-combinations* (make-array '(20 6)
:initial-contents
'((1 3 2 4 5 6)
(1 2 4 5 3 6)
(1 4 5 3 2 6)
(1 5 3 2 4 6)
(2 3 6 4 1 5)
(2 6 4 1 3 5)
(2 4 1 3 6 5)
(2 1 3 6 4 5)
(3 5 6 2 1 4)
(3 6 2 1 5 4)
(3 2 1 5 6 4)
(3 1 5 6 2 4)
(4 6 5 1 2 3)
(4 5 1 2 6 3)
(4 1 2 6 5 3)
(4 2 6 5 1 3)
(5 3 1 4 6 2)
(5 1 4 6 3 2)
(5 4 6 3 1 2)
(5 6 3 1 4 2))))

If you would notice, in every row the set of first and second elements together is unique. For e.g. the first row has (1, 3) and the second row has (1, 2).
Now I want to retrieve a specific row based on this given combination of first and second element. How do I do it?

[JosAH]

hrmph, I only noticed this thread today ...

If those first two numbers are both in a very narrow interval, e.g. [1,6] you can
synthesize a numerical index out of them, e.g 6*(i-1)+j-1 and use that as an index
in another array that stores the original arrays. A nil value would indicate no
array. For 20 arrays out of a possible 36 that isn't too bad.

Otherwise just a Java HashMap comes to mind where the first two numbers
form the key and the array itself forms the value in the Map.

kind regards,

Jos