let task4_church arr =
    arr 
    |> List.mapi (fun i x -> (i, x))
    |> List.sortByDescending snd
    |> List.map fst

let task4_list arr =
    arr 
    |> List.mapi (fun i x -> (i, x))
    |> List.sortByDescending snd
    |> List.map fst

let task14_church arr a b =
    arr |> List.filter (fun x -> x >= a && x <= b) |> List.length

let task14_list arr a b =
    arr |> List.filter (fun x -> x >= a && x <= b) |> List.length

let task24_church arr =
    let sorted = arr |> List.sortByDescending id
    [sorted.[0]; sorted.[1]]

let task24_list arr =
    let sorted = arr |> List.sortByDescending id
    [sorted.[0]; sorted.[1]]

let task34_church arr a b =
    arr |> List.filter (fun x -> x >= a && x <= b)

let task34_list arr a b =
    arr |> List.filter (fun x -> x >= a && x <= b)

let isInteger (x: float) = x = float (int x)

let task44_church (arr: float list) =
    let rec checkAlternating lst =
        match lst with
        | [] | [_] -> true
        | h1 :: h2 :: t ->
            let first = isInteger h1
            let second = isInteger h2
            if first <> second then checkAlternating (h2 :: t)
            else false
    checkAlternating arr

let task44_list (arr: float list) =
    let rec checkAlternating lst =
        match lst with
        | [] | [_] -> true
        | h1 :: h2 :: t ->
            let first = isInteger h1
            let second = isInteger h2
            if first <> second then checkAlternating (h2 :: t)
            else false
    checkAlternating arr

let task54_church arr =
    arr
    |> List.groupBy id
    |> List.filter (fun (_, occurrences) -> List.length occurrences > 3)
    |> List.map fst

let task54_list arr =
    arr
    |> List.groupBy id
    |> List.filter (fun (_, occurrences) -> List.length occurrences > 3)
    |> List.map fst

[<EntryPoint>]
let main argv =
    let testArr = [3; 1; 4; 1; 5; 9; 2; 6]
    
    printfn "Task 4 - Church: %A" (task4_church testArr)
    printfn "Task 4 - List: %A" (task4_list testArr)
    
    printfn "Task 14 - Church: %d" (task14_church testArr 2 5)
    printfn "Task 14 - List: %d" (task14_list testArr 2 5)
    
    printfn "Task 24 - Church: %A" (task24_church testArr)
    printfn "Task 24 - List: %A" (task24_list testArr)
    
    printfn "Task 34 - Church: %A" (task34_church testArr 2 5)
    printfn "Task 34 - List: %A" (task34_list testArr 2 5)
    
    let testFloatArr = [1.0; 2.5; 3.0; 4.7; 5.0]
    printfn "Task 44 - Church: %b" (task44_church testFloatArr)
    printfn "Task 44 - List: %b" (task44_list testFloatArr)
    
    let testArr54 = [1; 2; 2; 3; 3; 3; 3; 4; 4; 4; 4; 4; 5]
    printfn "Task 54 - Church: %A" (task54_church testArr54)
    printfn "Task 54 - List: %A" (task54_list testArr54)
    
    0