DouKaku? 456 ether: # uniq [3; 1; 4; 1; ...(アレイのuniq)

Comment detail

# uniq [3; 1; 4; 1; 5; 9; 2; 6; 5; 3; 5; 8; 9; 7; 9];;
- : int list = [3; 1; 4; 5; 9; 2; 6; 8; 7]

let uniq xs =
  let rec uniq' acc = function
  | [] -> acc
  | y::ys when (List.mem y acc) -> uniq' acc ys
  | y::ys -> uniq' (y::acc) ys
  in
  List.rev (uniq' [] xs)

#456 は「配列状」を緩く解釈してリストを使いましたが、文字通り配列（だけ）を使うとこうなるのかなあと。

let rec appears_between p q m a =
   if p = q then false
   else
     if a.(p) = m then true
     else appears_between (succ p) q m a

let uniq2 xs = 
  let ys = Array.copy xs in
  let rec move x y =
    if (Array.length xs) = x then
      Array.sub ys 0 y
    else
      if appears_between 0 y xs.(x) ys then
        move (succ x) y
      else
        (ys.(y) <- xs.(x); move (succ x) (succ y))
  in
  move 0 0

関数型ということにこだわらなければこういう手も。

open System;;
open Array;;

let uniq xs =
    let ars = create (length xs) xs.(0) in
    let i = ref 1 in
    for idx = 1 to (length xs)-1
    do
        if not (exists (fun elem -> xs.(idx) = elem) ars)
        then
            begin
                ars.(!i) <- xs.(idx);
                i := !i+1
            end
        else ()
    done;
    sub ars 0 !i;;

DouKaku?

Comment detail

Index

Feed

Other

Link

Pathtraq