coding_challenges.re

module Utils = {
  let rec repeat = (whatToRepeat, howManyTimes) =>
    switch howManyTimes {
    | 0 => ""
    | someNumber when howManyTimes > 0 => whatToRepeat ++ repeat(whatToRepeat, howManyTimes - 1)
    | _ => ""
    };
  let rec makePairFromList = (xs) =>
    switch xs {
    | [] => []
    | [a] => raise(Exit)
    | [f, s, ...tl] => [(f, s), ...makePairFromList(tl)]
    };
  let rec range = (x) =>
    switch x {
    | 0 => []
    | x when x > 0 => List.append([x], range(x - 1))
    | _ => []
    };
  let splitBy = (by, str) => Str.split(Str.regexp(by), str);
};

/* it assumes that list is int */
let getAverage = (xs) => (List.fold_left((+), 0, xs) |> float) /. (List.length(xs) |> float);

/* Digit Explode */
let digitsExplode = (str) =>
  Utils.splitBy("", str) |> List.map((x) => Utils.repeat(x, int_of_string(x)));

/* Parse */
type parse = {
  name: string,
  value: string
};

let parse = (str) =>
  Utils.splitBy(" ", str)
  |> Utils.makePairFromList
  |> List.map((x) => {name: fst(x), value: snd(x)});

let sumMultiplesBelow = (x) =>
  Utils.range(x - 1)
  |> List.filter((x) => x mod 3 === 0 || x mod 5 === 0)
  |> List.fold_left((+), 0);

let getDivisors = (x) => Utils.range(x) |> List.filter((id) => x mod id === 0) |> List.length;

let isAnagram = (s1, s2) => {
  let sortedS1 = List.sort(compare, Utils.splitBy("", s1));
  let sortedS2 = List.sort(compare, Utils.splitBy("", s2));
  sortedS1 === sortedS2
};