type loc = int * int

type pack_info = { weight : int; dest : int * int }

type pack_loc =
    No | Yes of loc | Maybe of loc (* | Likely of loc | Unlikely of loc *)

module IntMap = Map.Make
    (struct
      type t = int
      let compare = compare end)

let intmap_to_list m = IntMap.fold (fun id v acc -> (id, v) :: acc) m []

module IntSet = Set.Make
    (struct
      type t = int
      let compare = compare end)

module LocSet = Set.Make
    (struct
      type t = int * int
      let compare = compare end)

let intset_to_list m = IntSet.fold (fun e acc -> e :: acc) m []
let locset_to_list m = LocSet.elements m

type pack_list = (pack_info option * pack_loc) IntMap.t

type pack_id = int

type robot_info = { mutable robot_loc : int * int;
		    mutable own : IntSet.t }

type robot_list = robot_info IntMap.t

type map_elem = Plain | Water | Wall | Home of int (* num of packs taken *)

type map = map_elem array array

type move = N | E | S | W

type action = 
    Move of move
  | Pick of int list
  | Drop of int list


(* scalar loc and linear two-dim array *)

type fast_loc = int
type 'a fast_locarray = 'a array

let fastloc_y_shiftbits = 10
let fastloc_y_mult = 1024

let fastloc_get_x p = p land 1023
let fastloc_get_y p = p lsr 10
let fastloc_encode x y = (y lsl 10) lor x

let loc_of_fastloc p = fastloc_get_x p, fastloc_get_y p
let fastloc_of_loc (x, y) = fastloc_encode x y
let make_fastlocarray x y init = Array.create (y * fastloc_y_mult) init