solution week 285-2 -- Elixir

1 files changed, 30 insertions, 0 deletions

diff --git a/challenge-285/wambash/elixir/ch-2.exs b/challenge-285/wambash/elixir/ch-2.exs
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+++ b/challenge-285/wambash/elixir/ch-2.exs
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+defmodule Change do
+  defp _making({0,_}),do: [1]
+  defp _making({_,[]}),do: [0]
+  defp _making({amount, [hc| coins]}) when hc > amount, do: _making({amount,coins})
+  defp _making({amount, coins}) do
+    coins
+    |> Enum.flat_map(fn
+      x -> _making(
+        {
+          amount - x,
+          coins |> Enum.drop_while( & &1 > x )
+        }
+      )
+    end)
+  end
+  def making(w) do
+    _making(w) |> Enum.sum
+  end
+end
+
+ExUnit.start()
+
+defmodule ChangeTest do
+  use ExUnit.Case
+  test "Change" do
+    assert Change.making({9,[50,25,10,5,1]})  == 2
+    assert Change.making({100,[50,25,10,5,1]}) == 292
+    assert Change.making({15,[50,25,10,5,1]})  == 6
+  end
+end