On 27/08/2014 23:02, Alex Tweedly wrote:
I'll have a go at serializing this code - hopefully tonight (i.e.
starting now and not getting myself tied up in knots with it :-)
Here's a serialized version. Not as fast as I had hoped - it's about
twice as fst as the recursive vesion, but that means the non-duplicate
case ("abcdefghij") still takes about 13000ms, while the duplicated
versions are ("abcdabcdab") = 180 msec and "abbbbbbbbb" < 0
Remember .... I didn't say this code would be clear :-)
function serialpermut pMute
if the number of chars in pMute = 1 then return pMute
put empty into tOutput
-- an entry has
-- item 1 is a prefix
-- item 2 is the remaining set of chars to permute
-- tOutput contains the result of the permutation
put TAB & pMute &CR into todo
set the itemdel to TAB
repeat
if todo is empty then exit repeat
put todo into tDoing
put empty into todo
repeat for each line L in tDoing
put item 1 of L into tPrefix
put item 2 of L into tPerm
switch the number of chars in tPerm
case 1
put tPrefix & tPerm & CR after tOutput
break
case 2
put tPrefix & tPerm & CR after tOutput
if char 1 of tPerm <> char 2 of tPerm then put tPrefix &
char 2 of tPerm & char 1 of tPerm & CR after tOutput
break
default
put empty into tDone
repeat with i = 1 to the number of chars in tPerm
put char i of tPerm into c
if c is among the chars of tDone then next repeat
put c after tDone
put char 1 to i-1 of tPerm & char i+1 to -1 of tPerm
into temp
put tPrefix & c & TAB & temp & CR after todo
end repeat -- over chars in tPerm
end switch
end repeat
end repeat
return tOutput
end serialpermut
-- Alex.
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