819 - Most Common Word

Mix.install([])

ExUnit.start(auto_run: false)

Solution

https://leetcode.com/problems/most-common-word

defmodule Solution do
  @spec most_common_word(paragraph :: String.t(), banned :: [String.t()]) :: String.t()
  def most_common_word(paragraph, banned) do
    banned = Enum.map(banned, &String.downcase/1)

    paragraph
    |> String.downcase()
    |> String.splitter([" ", ",", ".", "!", "?", ";", "'"] ++ banned, trim: true)
    |> Enum.frequencies()
    |> Stream.map(fn {word, count} -> {count, word} end)
    |> Enum.sort(:desc)
    |> List.first()
    |> elem(1)
  end
end

defmodule TestSolution do
  use ExUnit.Case, async: false

  test "1" do
    assert Solution.most_common_word(
             "Bob hit a ball, the hit BALL flew far after it was hit.",
             ["hit"]
           ) == "ball"
  end
end

ExUnit.run()