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32 lines
817 B
Smalltalk
32 lines
817 B
Smalltalk
"Quicksort — Lomuto partition. Sorts an Array in place. Classic-corpus
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program for the Smalltalk-on-SX runtime."
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Object subclass: #Quicksort
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instanceVariableNames: ''!
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!Quicksort methodsFor: 'sort'!
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sort: arr ^ self sort: arr from: 1 to: arr size!
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sort: arr from: low to: high
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| p |
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low < high ifTrue: [
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p := self partition: arr from: low to: high.
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self sort: arr from: low to: p - 1.
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self sort: arr from: p + 1 to: high].
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^ arr!
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partition: arr from: low to: high
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| pivot i tmp |
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pivot := arr at: high.
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i := low - 1.
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low to: high - 1 do: [:j |
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(arr at: j) <= pivot ifTrue: [
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i := i + 1.
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tmp := arr at: i.
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arr at: i put: (arr at: j).
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arr at: j put: tmp]].
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tmp := arr at: i + 1.
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arr at: i + 1 put: (arr at: high).
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arr at: high put: tmp.
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^ i + 1! !
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