Permutations by swapping: Difference between revisions
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→{{header|ooRexx}}: add iterative version
Walterpachl (talk | contribs) m (→REXX ersion 1: seems to be faulty) |
Walterpachl (talk | contribs) m (→{{header|ooRexx}}: add iterative version) |
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=={{header|ooRexx}}==
===Recursive===
<lang oorexx>/* REXX Compute permutations of things elements */
/* implementing Heap's algorithm nicely shown in */
/* https://en.wikipedia.org/wiki/Heap%27s_algorithm */
/* Recursive Algorithm */
Parse Arg things
e.=''
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c b a
0 seconds</pre>
===Iterative===
/* REXX Compute permutations of things elements */
/* implementing Heap's algorithm nicely shown in */
/* https://en.wikipedia.org/wiki/Heap%27s_algorithm */
/* Iterative Algorithm */
Parse Arg things
e.=''
Select
When things='?' Then
Call help
When things='' Then
things=4
When words(things)>1 Then Do
elements=things
things=words(things)
Do i=0 By 1 While elements<>''
Parse Var elements e.i elements
End
End
Otherwise
If datatype(things)<>'NUM' Then Call help 'bunch ('bunch') must be numeric'
End
Do i=0 To things-1
a.i=i
End
Call time 'R'
Call generate things
Say time('E') 'seconds'
Exit
generate:
Parse Arg n
Call show
c.=0
i=0
Do While i<n
If c.i<i Then Do
if i//2=0 Then
Parse Value a.0 a.i With a.i a.0
Else Do
z=c.i
Parse Value a.z a.i With a.i a.z
End
Call show
c.i=c.i+1
i=0
End
Else Do
c.i=0
i=i+1
End
End
Return
show:
ol=''
Do j=0 To n-1
z=a.j
If e.0<>'' Then
ol=ol e.z
Else
ol=ol z
End
Say strip(ol)
Return
Exit
help:
Parse Arg msg
If msg<>'' Then Do
Say 'ERROR:' msg
Say ''
End
Say 'rexx permxi -> Permutations of 1 2 3 4 '
Say 'rexx permxi 2 -> Permutations of 1 2 '
Say 'rexx permxi a b c d -> Permutations of a b c d in 2 positions'
Exit</lang>
=={{header|Perl}}==
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