Permutations by swapping: Difference between revisions
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Add ooRexx and REXX version 2
(Added Algol 68) |
Walterpachl (talk | contribs) m (Add ooRexx and REXX version 2) |
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(perm: @[2, 1, 3, 0], sign: 1)
(perm: @[1, 2, 3, 0], sign: -1)</pre>
=={{header|ooRexx}}==
<lang oorexx>/* REXX Compute permutations of things elements */
/* implementing Heap's algorithm nicely shown in */
/* https://en.wikipedia.org/wiki/Heap%27s_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
n=0
Do i=0 To things-1
a.i=i
End
Call generate things
Say time('R') 'seconds'
Exit
generate: Procedure Expose a. n e. things
Parse Arg k
If k=1 Then
Call show
Else Do
Call generate k-1
Do i=0 To k-2
ka=k-1
If k//2=0 Then
Parse Value a.i a.ka With a.ka a.i
Else
Parse Value a.0 a.ka With a.ka a.0
Call generate k-1
End
End
Return
show: Procedure Expose a. n e. things
n=n+1
ol=''
Do i=0 To things-1
z=a.i
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 permx -> Permutations of 1 2 3 4 '
Say 'rexx permx 2 -> Permutations of 1 2 '
Say 'rexx permx a b c d -> Permutations of a b c d in 2 positions'
Exit</lang>
{{out}}
<pre>H:\>rexx permx ?
rexx permx -> Permutations of 1 2 3 4
rexx permx 2 -> Permutations of 1 2
rexx permx a b c d -> Permutations of a b c d in 2 positions
H:\>rexx permx 2
0 1
1 0
0 seconds
H:\>rexx permx a b c
a b c
b a c
c a b
a c b
b c a
c b a
0 seconds</pre>
=={{header|Perl}}==
Line 2,691 ⟶ 2,781:
=={{header|REXX}}==
===Version 1===
<lang rexx>/*REXX program generates all permutations of N different objects by swapping. */
parse arg things bunch . /*obtain optional arguments from the CL*/
Line 2,769 ⟶ 2,860:
</pre>
===Version 2===
See program shown for ooRexx
=={{header|Ruby}}==
{{trans|BBC BASIC}}
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