Contents

defmodule PascalsTriangle do
  @doc """
  Calculates the rows of a pascal triangle
  with the given height
  """
  @spec rows(integer) :: [[integer]]
  def rows(num) do
    do_rows(num - 1, [[1]])
  end

  defp do_rows(0, rows), do: Enum.reverse rows
  defp do_rows(n, rows = [h | _]) do
    do_rows(n - 1, [next_row(h) | rows])
  end

  defp next_row(list) do
    list
    |> each_cons
    |> Enum.map(fn [a, b] -> a + b end)
    |> add_ends
  end

  defp each_cons(list) do
    list
    |> Enum.flat_map(&[&1, &1])
    |> Enum.slice(1..-2)
    |> Enum.chunk(2)
  end

  defp add_ends(list), do: [1] ++ list ++ [1]
end

Version data entries

327 entries across 327 versions & 1 rubygems

Version	Path
trackler-2.2.1.29	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.28	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.27	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.26	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.25	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.24	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.23	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.22	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.21	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.20	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.19	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.18	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.17	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.16	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.15	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.14	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.13	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.12	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.11	tracks/elixir/exercises/pascals-triangle/example.exs
trackler-2.2.1.10	tracks/elixir/exercises/pascals-triangle/example.exs