\(  Calculate all permutations of integers 1..n

    General variant: simple, single array, recursive, not in lexical order
    A row with n places is used, initially 0.
    The current element l replaces the free places one by one,
    and the next element l+1 is probed with the array.
\)
\C  Use publication mode with keywords instead of symbols
permute1 (l) to (n) fill (r):
  if l > n
    print join r            \ output requires most of CPU time
    return
  for j = from 1 upto n
    if r[j] == 0
      r[j] = l
      permute1 l+1 to n fill r
      r[j] = 0

\(  command line parameter is number of elements
\)
main (parms):+
  n = string parms[1] as integer else 3
  r = new row size n init 0
  permute1 1 to n fill r