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type ChurchList<'a> = ('a -> 'b -> 'b) -> 'b -> 'b
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let nil : ChurchList<'a> = fun _ z -> z
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let cons (x: 'a) (xs: ChurchList<'a>) : ChurchList<'a> =
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fun f z -> f x (xs f z)
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let toList (churchList: ChurchList<'a>) : 'a list =
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churchList (fun x acc -> x :: acc) []
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|> List.rev
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let ofList (lst: 'a list) : ChurchList<'a> =
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List.foldBack cons lst nil
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let foldWithPredicate (f: 'a -> 'b -> 'b) (p: 'a -> bool) (acc: 'b) (churchList: ChurchList<'a>) : 'b =
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let rec foldTailRec lst currentAcc =
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match lst with
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| [] -> currentAcc
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| x :: xs ->
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if p x then
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foldTailRec xs (f x currentAcc)
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else
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foldTailRec xs currentAcc
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let regularList = toList churchList
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foldTailRec regularList acc
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let findMin (churchList: ChurchList<int>) : int option =
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let regularList = toList churchList
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match regularList with
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| [] -> None
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| x :: xs ->
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let minValue = foldWithPredicate (fun x acc -> min x acc) (fun _ -> true) x churchList
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Some minValue
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let sumEven (churchList: ChurchList<int>) : int =
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foldWithPredicate (+) (fun x -> x % 2 = 0) 0 churchList
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let countOdd (churchList: ChurchList<int>) : int =
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foldWithPredicate (fun _ acc -> acc + 1) (fun x -> x % 2 <> 0) 0 churchList
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[<EntryPoint>]
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let main argv =
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let testList = ofList [1; 2; 3; 4; 5; 6; 7; 8; 9; 10]
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let emptyList = nil
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printfn "Тестовый список: [1; 2; 3; 4; 5; 6; 7; 8; 9; 10]"
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match findMin testList with
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| Some min -> printfn "Минимальный элемент: %d" min
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| None -> printfn "Список пуст"
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printfn "Сумма четных чисел: %d" (sumEven testList)
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printfn "Количество нечетных чисел: %d" (countOdd testList)
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printfn "\nТест с пустым списком:"
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match findMin emptyList with
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| Some min -> printfn "Минимальный элемент: %d" min
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| None -> printfn "Список пуст"
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printfn "Сумма четных чисел в пустом списке: %d" (sumEven emptyList)
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printfn "Количество нечетных чисел в пустом списке: %d" (countOdd emptyList)
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0 |
