用 Elixir 計算 anagram

Anagram（易位構詞）是把某個單字或片語的字母重新排列後形成的另一個單字或片語，通常每個原始字母都恰好使用一次

例如：

• "restful" = "fluster"
• "funeral" = "real fun"
• "adultery" = "true lady"
• "customers" = "store scum"
• "forty five" = "over fifty"

用 mix new anagram 建立一個新專案，然後我們來寫一些測試案例：

defmodule AnagramTest do
  use ExUnit.Case

  test "calculates anagram" do
    assert Anagram.anagram?("restful", "fluster") == true
    assert Anagram.anagram?("funeral", "realfun") == true
    assert Anagram.anagram?("adultery", "truelady") == true
    assert Anagram.anagram?("customers", "storescum") == true
    assert Anagram.anagram?("fortyfive", "overfifty") == true
    assert Anagram.anagram?("fiftyfive", "overfifty") == false
    assert Anagram.anagram?("funeral", "real fun") == false
  end
end

接下來我們要寫程式碼：

defmodule Anagram do
    def anagram?(a, b) do
    charlist(a) == charlist(b)
  end

  def charlist(w) do
    w |> String.trim() |> String.downcase() |> String.graphemes() |> Enum.sort()
  end
end

執行測試 mix test：

Compiling 1 file (.ex)
Generated anagram app
.

Finished in 0.1 seconds
1 test, 0 failures

Randomized with seed 752850

完成，現在你有一個 anagram 計算器了！