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@evadne evadne/xmastree.ex
Last active Dec 16, 2019

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Christmas Trees in Elixir
defmodule Tree do
def print(n) do
for i <- 1 .. n do
p(n - i, " ")
p(i * 2 - 1, "*")
w("\n")
end
p(n - 1, " ")
w("|\n")
end
defp p(n, x)
defp p(0, _), do: :ok
defp p(n, x), do: for _ <- 1 .. n, do: w(x)
defp w(x), do: IO.write(x)
end
defmodule BloatedTree do
def print(n) do
for i <- 1 .. n, do: p(d(n - i, " ") <> d(i * 2 - 1, "*"))
p(d(n - 1, " ") <> "|")
end
defp d(n, s), do: String.duplicate(s, n)
defp p(x), do: IO.puts(x)
end
defmodule SinglePrintTree do
def print(n) do
leaves = for i <- 1 .. n, do: d(n - i, " ") <> d(i * 2 - 1, "*")
stem = d(n - 1, " ") <> "|"
IO.puts(Enum.join(leaves ++ [stem], "\n"))
end
defp d(n, s), do: String.duplicate(s, n)
end
defmodule SinglePrintIOListTree do
def print(n) do
leaves = for i <- 1 .. n, do: [d(n - i, " "), d(i * 2 - 1, "*"), "\n"]
stem = [d(n - 1, " "), "|"]
IO.puts [leaves, stem]
end
defp d(n, s), do: String.duplicate(s, n)
end
defmodule SinglePrintNoDuplicateIOListTree do
def print(n) do
leaves = for i <- 1 .. n, do: [d(n - i, " "), d(i * 2 - 1, "*"), "\n"]
stem = [d(n - 1, " "), "|"]
IO.puts [leaves, stem]
end
defp d(n, s, a \\ [])
defp d(0, _, a), do: a
defp d(n, s, a), do: d(n - 1, s, [s | a])
end
test = fn ->
for x <- 1 .. 10 do
{a, _} = :timer.tc(fn ->
for _ <- 1 .. 1000, do: Tree.print(x)
end)
{b, _} = :timer.tc(fn ->
for _ <- 1 .. 1000, do: BloatedTree.print(x)
end)
{c, _} = :timer.tc(fn ->
for _ <- 1 .. 1000, do: SinglePrintTree.print(x)
end)
{d, _} = :timer.tc(fn ->
for _ <- 1 .. 1000, do: SinglePrintIOListTree.print(x)
end)
{e, _} = :timer.tc(fn ->
for _ <- 1 .. 1000, do: SinglePrintNoDuplicateIOListTree.print(x)
end)
{x, a, b, c, d, e}
end
end
((fn ->
#
# With I/O to STDIO
#
# [
# {1, 12529, 9639, 5628, 4913, 5047},
# {2, 40616, 15349, 4672, 5342, 7255},
# {3, 86754, 42744, 13583, 15537, 16900},
# {4, 179915, 23662, 10248, 6174, 9779},
# {5, 199164, 29099, 8647, 6944, 8353},
# {6, 275208, 33379, 9747, 7681, 7818},
# {7, 373047, 40429, 14440, 11855, 11288},
# {8, 532534, 42508, 17121, 31591, 16638},
# {9, 566551, 48979, 11900, 21552, 12687},
# {10, 723348, 55072, 12314, 24258, 14422}
# ]
#
test.() |> IO.inspect
end).())
((fn ->
#
# Without I/O to STDIO via I/O capturing in ExUnit
#
# [
# {1, 5053, 4624, 3391, 2768, 2130},
# {2, 14860, 6711, 3154, 2536, 2491},
# {3, 34378, 14339, 6651, 4077, 4985},
# {4, 64317, 14771, 5655, 4150, 5587},
# {5, 151442, 21348, 7600, 5281, 5953},
# {6, 149298, 17912, 6075, 4475, 9791},
# {7, 174312, 18847, 6975, 4240, 5562},
# {8, 210175, 22379, 7177, 4889, 7097},
# {9, 254250, 25438, 9082, 5199, 7628},
# {10, 342061, 56717, 18038, 10416, 19400}
# ]
#
{:ok, result_agent} = Agent.start_link(fn -> nil end)
ExUnit.CaptureIO.capture_io(fn ->
result = test.()
Agent.update(result_agent, fn _ -> result end)
end)
Agent.get(result_agent, fn x -> x end) |> IO.inspect
end).())
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