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Permutations: Difference between revisions
Add explicit solution in Smalltalk
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Line 5,266:
<lang smalltalk>(1 to: 4) permutationsDo: [ :x |
Transcript show: x printString; cr ].</lang>
{{works with|GNU Smalltalk}}
<lang smalltalk>
ArrayedCollection extend [
permuteAndDo: aBlock
["Permute receiver in-place, and call aBlock.
Requires integer keys."
self permuteUpto: self size andDo: aBlock]
permuteUpto: n andDo: aBlock
[n = 0 ifTrue: [^aBlock value].
1 to: n do:
[:i |
self swap: i with: n.
self permuteUpto: n-1 andDo: aBlock.
self swap: i with: n]]
]
SequenceableCollection extend [
permutations
["Answer a ReadStream of permuted shallow copies of receiver."
| c |
c := MappedCollection
collection: self
map: self keys asArray.
^Generator on:
[:g |
c map permuteAndDo: [g yield: (c copyFrom: 1 to: c size)]]]
</lang>
=={{header|Stata}}==
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