SimpleTask__Ocaml__

(*Karol Dziachan*)

(*task 1 - create the function, which the list of lists is flattened by one level*)

let rec flatten list=
   List.hd list @  List.hd (List.tl list);;


flatten[[1;2;3];[4;5;6]] = [1;2;3;4;5;6];;
flatten[[];[1;2;3]] = [1;2;3];;
flatten[[4;5;6];[]] = [4;5;6];;
flatten[[];[]] = [];;

(* task 2*)

let rec count (x,xs) =
    if xs == [] then failwith ("empty list")
      else if List.tl xs ==  [] then 1
         else if List.hd xs == x then 1+count(x, List.tl xs)
    else count(x , List.tl xs);;

count('a', ['a';'l';'a']) = 2;;
count('a', ['a';'l';'a';'a';'m';'a'])= 4;;
count(1, [1;2;3;1;3;1;5;3;1]) = 4;;
count('a', []);;

(* task3 *)

let rec replicate (x, n) =
  if(n==1) then x
     else if(n==0) then failwith ("nothing")
  else x @ replicate(x, n-1);;

replicate(["la"], 3);;
replicate([""], 3);;
replicate(["la"], 0);;
replicate([""], 0);;

(*task 4*)

let rec sqrtList xs =
  if xs==[] then failwith ("nothing")
     else if List.tl xs != [] then  (List.hd xs)*(List.hd xs) :: (sqrtList(List.tl xs))
  else   List.tl xs @ ([(List.hd xs)*(List.hd xs)]);;

sqrtList[1;2;3;(-4)];;

(* task 5 *)

let rec palindrome xs =
  if xs == [] then failwith ("empty list")
   else
     xs=(List.rev xs);;


  palindrome["a";"l";"a"];;
  palindrome["k";"a";"j";"a";"k"];;
  palindrome["k";"a";"r";"o";"l"];;
  palindrome["A";"l";"a"];;
  palindrome[];;

  (*task 6*)

 let rec listLength xs=
            if(xs == []) then failwith ("empty lity")
            else if (List.tl xs != []) then 1+listLength(List.tl xs)
            else 1;;


   listLength[1;2;3;4;5];;
   listLength["k";"a";"r";"o";"l"];;
   listLength["mother"];;
   listLength["mother"; "father"];;
   listLength[];;