Find all permutations of integers 1 to n

* This macro finds all permutations of the integers 1, 2, ... t where t < 8.
* Raynald Levesque Feb. 2002.


DEFINE !t(nb=!TOKENS(1))

/* Create a file containing all combinations (with replacements)*/.
INPUT PROGRAM.
!DO !cnt=1 !TO !nb
LOOP !CONCAT('cnt',!cnt,'=1 TO ',!nb).
LEAVE !CONCAT('cnt',!cnt).
!DOEND
END CASE.
!DO !cnt=1 !TO !nb.
END LOOP.
!DOEND
END FILE.
END INPUT PROGRAM.

* Count if some number appears more than once.
NUMERIC c1 TO !CONCAT('c',!nb).
!DO !cnt=1 !TO !nb
COUNT !CONCAT('c',!cnt,' =cnt1 TO c',!cnt,'(',!cnt,')').
!DOEND

/* Keep only true permutations (without replacements)*/.
SELECT IF MAX(c1 TO !CONCAT('c',!nb))=1.
EXECUTE.
STRING newname(A8).
COMPUTE newname=CONCAT('p',LTRIM(STRING($CASENUM,F8.0))).

FLIP cnt1 TO !CONCAT('cnt',!nb) /NEWNAMES=newname.

SAVE OUTFILE='c:\\temp\\all permutations.sav' /DROP=case_lbl.
!ENDDEFINE.

!t nb=6.