ABC043C - いっしょ

問題

https://atcoder.jp/contests/abc043/tasks/arc059_a

回答1

defmodule Main do
  def main do
    :stdio
    |> IO.read(:all)
    |> solve()
    |> IO.puts()
  end

  defp split_lines(lines) do
    lines
    |> String.trim()
    |> String.split("\n")
  end

  defp split_words(words) do
    String.split(words, " ")
  end

  def solve(input) do
    a =
      input
      |> String.trim()
      |> split_lines()
      |> Enum.at(1)
      |> split_words()
      |> Enum.map(&String.to_integer/1)

    mean =
      (Enum.sum(a) / length(a))
      |> round()

    a
    |> Enum.map(fn a_i ->
      :math.pow(a_i - mean, 2)
    end)
    |> Enum.sum()
    |> floor()
  end
end

"""
2
4 8
"""
|> Main.solve()
|> then(&(&1 == 8))

"""
3
1 1 3
"""
|> Main.solve()
|> then(&(&1 == 3))

"""
3
4 2 5
"""
|> Main.solve()
|> then(&(&1 == 5))

"""
4
-100 -100 -100 -100
"""
|> Main.solve()
|> then(&(&1 == 0))