> let mutable map:Map<int, int> = Map.empty;;
val mutable map : Map<int,int> = map []
> let rec get_prime_factor (map:Map<int, int> byref) (n:int) (factor: int) =
- if n >= factor then
- if n % factor <> 0 then
- get_prime_factor &map n (factor + 1)
- else
- if Map.containsKey factor map then
- let n = map.[factor] + 1
- map <- map.Remove factor
- map <- (map |> Map.add factor n)
- else
- map <- (map |> Map.add factor 1)
-
- get_prime_factor &map (n / factor) factor
- ;;
val get_prime_factor : byref<Map<int,int>> -> int -> int -> unit
> get_prime_factor &map 28 2;;
val it : unit = ()
> map
- ;;
val it : Map<int,int> = map [(2, 2); (7, 1)]
> map
- |> Map.iter (fun k t -> printf "%d -> %d\n" k t)
- ;;
2 -> 2
7 -> 1
val it : unit = ()
> map
- |> Map.map (fun k t -> System.Math.Pow(float k,float t))
- ;;
val it : Map<int,float> = map [(2, 4.0); (7, 7.0)]
> map
- |> Map.map (fun k t -> System.Math.Pow(float k,(float t) + 1.0))
- ;;
val it : Map<int,float> = map [(2, 8.0); (7, 49.0)]
> map
- |> Map.map (fun k t -> System.Math.Pow(float k,(float t) + 1.0) - 1.0)
- ;;
val it : Map<int,float> = map [(2, 7.0); (7, 48.0)]
> map
- |> Map.map (fun k t -> (System.Math.Pow(float k,(float t) + 1.0) - 1.0) / float (k - 1))
- ;;
val it : Map<int,float> = map [(2, 7.0); (7, 8.0)]
> map
- |> Map.map (fun k t -> (System.Math.Pow(float k,(float t) + 1.0) - 1.0) / float (k - 1))
- |> Map.toList
- ;;
val it : (int * float) list = [(2, 7.0); (7, 8.0)]
> map
- |> Map.map (fun k t -> (System.Math.Pow(float k,(float t) + 1.0) - 1.0) / float (k - 1))
- |> Map.toList
- |> List.map (fun (k, t) -> t)
- ;;
val it : float list = [7.0; 8.0]
> map
- |> Map.map (fun k t -> (System.Math.Pow(float k,(float t) + 1.0) - 1.0) / float (k - 1))
- |> Map.toList
- |> List.map (fun (k, t) -> t)
- |> List.reduce(*)
- ;;
val it : float = 56.0
> int (map
- |> Map.map (fun k t -> (System.Math.Pow(float k,(float t) + 1.0) - 1.0) / float (k - 1))
- |> Map.toList
- |> List.map (fun (k, t) -> t)
- |> List.reduce(*))
- ;;
val it : int = 56
> let sum_of_proper_divisors (n:int):int =
- let mutable map:Map<int, int> = Map.empty
- get_prime_factor &map n 2
-
- if map.IsEmpty then 0
- else
- int (map
- |> Map.map (fun k t -> (System.Math.Pow(float k,(float t) + 1.0) - 1.0) / float (k - 1))
- |> Map.toList
- |> List.map (fun (k, t) -> t)
- |> List.reduce(*)) - n
- ;;
val sum_of_proper_divisors : int -> int
> sum_of_proper_divisors 220;;
val it : int = 284
> sum_of_proper_divisors 284;;
val it : int = 220
>
- let mutable ami_list:List<int> = [];;
val mutable ami_list : List<int> = []
> for i in [1 .. 10000] do
- let n = sum_of_proper_divisors i
- if i <> n then
- let m = sum_of_proper_divisors n
- if i = m then ami_list <- n::ami_list
- ;;
val it : unit = ()
> ami_list
- ;;
val it : List<int> =
[6232; 6368; 5020; 5564; 2620; 2924; 1184; 1210; 220; 284]
> ami_list
- |> List.reduce(+)
- ;;
val it : int = 31626
