Hello,
I am thinking about a little tool to print all combinations of a string with length 3.
On each pos can be 'A' or 'B' or 'C'.
So I know that it gives 3 * 3 = 27 combinations
AAA
BBB
CCC
...
Anyone an idea to do this lispisch in newLISP?
Generic algo possible with variable length and variable number of possible chars?
Got it:
(dolist (x '("A" "B" "C"))(dolist (y '("A" "B" "C"))(dolist (z '("A" "B" "C"))(println(string x y z)))))
Any better?
My candidate:
(define (permuations lst i)
(if (= i 1)
;; if i = 1, then just return the list
lst
;; otherwise permutate the list with the permutations of i-1
(apply append
(map (fn (x)
(map (fn (y) (append x y))
lst))
(permuations lst (- i 1)))
2)))
(println (permuations lst 3))
(exit)
Note that mine doesn't just print the items, but generates a list of them, which is probably more useful in most situations.