We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. Prepare
  2. Functional Programming
  3. Introduction
  4. Filter Positions in a List
  5. Discussions

Filter Positions in a List

Sort by

recency

|

185 Discussions

|

  • nemay81983
     + 0 comments

    Thanks! This solution works perfectly. I used it to filter out unnecessary data from my list before I proceed to track paxi shipments more accurately.

  • werhdy3
     + 0 comments

    It can be done like this too : Range(1,arr.length,2).map(x=>arr(x)).toList

  • achraf_crispy
     + 0 comments

    Solution in Ocaml without using builtins function:

    let read_inputs () =
  let rec get_inputs liste =
    try
      let tmp = read_int () in
      get_inputs (liste @ [tmp])  (* Accumulate input into the list *)
    with
    | End_of_file -> liste
  in
  get_inputs [] ;;
  
 let rec filter_odd_position_element liste n = 
    if n <> List.length liste && (n mod 2) = 1 then
        Printf.printf "%d\n" (List.nth liste n);
    if n <> List.length liste then
         filter_odd_position_element liste (n + 1) ;;
let liste = read_inputs ();;
 filter_odd_position_element liste 0;;

  • napster007
     + 0 comments

    Scala one liner: arr.grouped(2).map(_.tail).flatten.toList

  • ddebajyati
     + 0 comments

    Solution in OCaml

    (* Enter your code here. Read input from STDIN. Print output to STDOUT *)
let rec read_lines acc = try
    let line = input_line stdin |> int_of_string in
    read_lines (line :: acc)
  with End_of_file -> List.rev acc;;

let arr = read_lines [];;

(* This commented code below increased space complexity in my previous submission
let len = List.length arr;;

let rec range start stop step acc =
  if start >= stop then
    List.rev acc
  else
    range (start + step) stop step (start :: acc);;

let indices = range 0 len 1 [];;

let pairs = List.combine indices arr;;*)

(* Better code is here below *)
let enumerate lst =
  List.mapi (fun index elem -> (index, elem)) lst;;

let pairs = enumerate arr;;

let result = List.filter (fun (index,el) -> index mod 2 <> 0) pairs;;

let () = 
  List.iter (fun (index, el) -> print_endline (string_of_int el)) result;;