Permutations: Difference between revisions

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<br>but that would make it specific to numbers and not "things" or objects.

<lang rexx>/*REXX program generates all permutations of N different objects. */

parse arg things bunch inbetweenChars names

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call permSets things,bunch,inbetweenChars,names

exit /*stick a fork in it, we're done.*/

/*──────────────────────────────────.PERMSET subroutine─────────────────*/

⚫

.permset: procedure expose (list); parse arg ?

⚫

if ?>y then do; _=@.1; do j=2 to y; _=_||between||@.j; end; say _; end

⚫

else do q=1 for x /*build permutation recursively. */

⚫

do k=1 for ?-1; if @.k==$.q then iterate q; end /*k*/

⚫

@.?=$.q; call .permset(?+1)

⚫

end /*q*/

⚫

return

/*──────────────────────────────────PERMSETS subroutine─────────────────*/

permSets: procedure; parse arg x,y,between,uSyms /*X things Y at a time.*/

@.=; sep= /*X can't be > length(@0abcs). */

@abc='abcdefghijklmnopqrstuvwxyz'; @abcU=@abc; upper @abcU

@abc = 'abcdefghijklmnopqrstuvwxyz'; @abcU=@abc; upper @abcU

@abcS=@abcU||@abc; @0abcS=123456789||@abcS

@abcS = @abcU || @abc; @0abcS=123456789 || @abcS

do k=1 for x /*build a list of (perm) symbols.*/

_=p(word(uSyms,k) p(substr(@0abcS,k,1) k)) /*get or generate a symbol.*/

_=p(word(uSyms,k) p(substr(@0abcS,k,1) k)) /*get|generate a symbol.*/

if length(_)\==1 then sep='_' /*if not 1st char, then use sep. */

$.k=_ /*append it to the symbol list. */

end

if between=='' then between=sep /*use the appropriate seperator. */

list='$. @. between x y'

call permset(1)

call .permset(1)

⚫

return

/*──────────────────────────────────PERMSET subroutine──────────────────*/

⚫

permset: procedure expose (list); parse arg ?

⚫

if ?>y then do; _=@.1; do j=2 to y; _=_||between||@.j; end; say _; end

⚫

else do q=1 for x /*build permutation recursively. */

⚫

do k=1 for ?-1; if @.k==$.q then iterate q; end /*k*/

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@.?=$.q; call permset(?+1)

⚫

end /*q*/

return

/*──────────────────────────────────P subroutine (Pick one)─────────────*/

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platypus-stegosaurus-gnu

</pre>

===version 2===

This version is modeled after the Maxima program (as far as output).