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57 lines
1.7 KiB
Plaintext
57 lines
1.7 KiB
Plaintext
app Quicksort provides [ main ] imports []
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main =
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quicksort : List (Num a) -> List (Num a)
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quicksort = \list ->
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quicksortHelp list 0 (List.len list - 1)
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quicksortHelp : List (Num a), Int, Int -> List (Num a)
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quicksortHelp = \list, low, high ->
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when partition low high list is
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Pair partitionIndex partitioned ->
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partitioned
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|> quicksortHelp low (partitionIndex - 1)
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|> quicksortHelp (partitionIndex + 1) high
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swap : Int, Int, List a -> List a
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swap = \i, j, list ->
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when Pair (List.get list i) (List.get list j) is
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Pair (Ok atI) (Ok atJ) ->
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list
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|> List.set i atJ
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|> List.set j atI
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_ ->
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[]
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partition : Int, Int, List (Num a) -> [ Pair Int (List (Num a)) ]
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partition = \low, high, initialList ->
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when List.get initialList high is
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Ok pivot ->
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go = \i, j, list ->
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if j < high then
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when List.get list j is
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Ok value ->
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if value <= pivot then
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go (i + 1) (j + 1) (swap (i + 1) j list)
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else
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go i (j + 1) list
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Err _ ->
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Pair i list
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else
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Pair i list
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when go (low - 1) low initialList is
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Pair newI newList ->
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Pair (newI + 1) (swap (newI + 1) high newList)
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Err _ ->
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Pair (low - 1) initialList
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quicksort [ 7, 19, 4, 21 ]
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