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75 lines
2.1 KiB
Text
75 lines
2.1 KiB
Text
interface Quicksort exposes [sortBy, sortWith, show] imports []
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show : List I64 -> Str
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show = \list ->
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if List.isEmpty list then
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"[]"
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else
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content =
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list
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|> List.map Num.toStr
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|> Str.joinWith ", "
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"[\(content)]"
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sortBy : List a, (a -> Num *) -> List a
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sortBy = \list, toComparable ->
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sortWith list (\x, y -> Num.compare (toComparable x) (toComparable y))
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Order a : a, a -> [LT, GT, EQ]
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sortWith : List a, (a, a -> [LT, GT, EQ]) -> List a
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sortWith = \list, order ->
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n = List.len list
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quicksortHelp list order 0 (n - 1)
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quicksortHelp : List a, Order a, Nat, Nat -> List a
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quicksortHelp = \list, order, low, high ->
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if low < high then
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when partition low high list order is
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Pair partitionIndex partitioned ->
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partitioned
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|> quicksortHelp order low (Num.subSaturated partitionIndex 1)
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|> quicksortHelp order (partitionIndex + 1) high
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else
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list
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partition : Nat, Nat, List a, Order a -> [Pair Nat (List a)]
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partition = \low, high, initialList, order ->
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when List.get initialList high is
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Ok pivot ->
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when partitionHelp low low initialList order high pivot is
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Pair newI newList ->
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Pair newI (swap newI high newList)
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Err _ ->
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Pair low initialList
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partitionHelp : Nat, Nat, List c, Order c, Nat, c -> [Pair Nat (List c)]
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partitionHelp = \i, j, list, order, high, pivot ->
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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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when order value pivot is
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LT | EQ ->
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partitionHelp (i + 1) (j + 1) (swap i j list) order high pivot
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GT ->
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partitionHelp i (j + 1) list order high pivot
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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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swap : Nat, Nat, 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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