file8.ml

let combine1 l =
  let rec aux acc lst = match lst with
    | [] -> acc
    | h::t -> aux (h@acc) t
  in aux [] (List.rev l)

let combine2 l = List.fold_right (fun el acc -> el@acc) l []
let combine3 l = List.fold_left (fun acc el -> el@acc) [] l

let mylst = [[1;2]; [3;4;5]; []; [6]]

let sumPair1 l =
  let rec aux acc1 acc2 lst = match lst with
    | [] -> (acc1, acc2)
    | h::t -> match h with
              | (a, b) -> aux (acc1+a) (acc2+b) t
  in aux 0 0 l

let mylst2 = [(1, 2); (4, 5); (5, 7); (9, 11)]

let sumPair2 l = List.fold_right (fun (a, b) (x, y) -> (x+a, y+b)) l (0, 0)

let nrEl l = List.fold_right (fun el acc -> acc+1) l 0

let maxLst l = List.fold_right (fun el acc -> if el > acc then el else acc) l 0

let lstComp l1 l2 =
  let rec aux lst1 lst2 = match lst1, lst2 with
    | [], [] -> 0
    | [], a -> -1
    | a, [] -> 1
    | h1::t1, h2::t2 -> if h1 = h2 then aux t1 t2 else
                          if h1 > h2 then 1 else -1
  in aux l1 l2

let lsta = [1; 2; 3; 4]

let fromTo a b =
  let rec aux acc n =
    if n = a then n::acc
    else aux (n::acc) (n-1)
  in aux [] b

let xlst = fromTo 1 100

let prod =  List.fold_right
              (fun el acc -> if (el mod 2) != 0 then el * acc else acc) xlst 1

let cuburi = List.fold_right
               (fun el acc -> if (el mod 5) = 0 then (el*el*el)+acc else acc) xlst 0

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

let seta = IS.add 3 (IS.add 7 (IS.add 5 (IS.singleton(1))))

let setb = IS.add 2 (IS.add 1 (IS.add 6 (IS.add 4 (IS.singleton(3)))))

let myinter set1 set2 = IS.fold (fun el acc -> if IS.mem el set2 then IS.add el acc else acc) set1 IS.empty

let myreun set1 set2 = IS.fold (fun el acc -> IS.add el acc) set1 set2

let mydiff set1 set2 = IS.fold (fun el acc -> if not (IS.mem el set2) then IS.add el acc else acc) set1 IS.empty