QuickSort

StarLogo TIPS

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†

sort-num-list [3 1 2]

reverse (sort-num-list [3 1 2])

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to qsort :s
 if(:s = []) [ output []]
 let [:gl (partg (first :s) (butfirst :s))]
 let [:ll (partl (first :s) (butfirst :s))]
 let [:sgl (qsort :gl)]
 let [:sll (qsort :ll)]
 output (sentence :sgl (fput (first :s) :sll))
end

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to partg :a :s
 if(:s = []) [ output [] ]
 let [:val1 :a]
 let [:val2 (first :s)]
 ifelse :val1 < :val2 [
     output (fput (first :s) (partg :a (butfirst :s)))
 ][
     output (partg :a (butfirst :s))
 ]
end

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to partl :a :s
 if(:s = []) [ output [] ]
 let [:val1 :a]
 let [:val2 (first :s)]
 ifelse :val1 < :val2 [
     output (partl :a (butfirst :s))
 ][
     output (fput (first :s) (partl :a (butfirst :s)))
 ]
end

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print partg 5 [4 2 6 8]
print partl 5 [4 2 6 8]
print qsort [5 4 2 6 8]

[8 6]
[2 4]
[8 6 5 4 2]