#require "fmt"
(* #directory "_build/src" *)
(* #load "psq.cma" *)

let shuff arr =
  let n = Array.length arr in
  for i = 0 to n - 2 do
    let j = Random.int (n - i) + i in
    let t = arr.(i) in
    arr.(i) <- arr.(j);
    arr.(j) <- t
  done

let permutation n =
  let arr = Array.init n (fun x -> x) in
  shuff arr;
  Array.to_list arr

let rec (--) a b = if a > b then [] else a :: succ a -- b

module I = struct type t = int let compare = compare end
module Q = Psq.Make (I) (I)

let pp_q = Q.pp_dump Fmt.int Fmt.int
;;
#install_printer pp_q