Submission #169616

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Source Code Expand

let ( |> ) x f = f x

let repeat f =
  let rec loop acc = function
    | 0 -> List.rev acc
    | n -> loop (f () :: acc) (n - 1) in
  loop []

let rec remove x = function
  | [] -> []
  | y :: ys ->
      if x = y then ys
      else y :: remove x ys

let rec permutation = function
  | [] -> [[]]
  | xs ->
      List.flatten (List.map (fun x ->
        List.map (fun ys -> x :: ys)
          (permutation (remove x xs))) xs)

let rec turn = function 
  | [] -> []
  | (n, i) :: ns -> (n, i) :: List.map (fun (n', i') ->
      if n' mod n = 0 then (n', i' + 1)
      else (n', i')) (turn ns)
let turn ns =
  ns
  |> List.map (fun n -> (n, 0))
  |> turn
  |> List.filter (fun (_, i) -> i mod 2 = 0)
  |> List.map fst

let average ns =
  float_of_int (List.fold_left ( + ) 0 ns) /. float_of_int (List.length ns)

let () =
  read_int ()
  |> repeat read_int
  |> permutation
  |> List.map turn
  |> List.map List.length
  |> average
  |> Printf.printf "%f\n"

Submission Info

Judge Result