1 files changed, 77 insertions, 0 deletions
diff --git a/challenge-283/packy-anderson/elixir/ch-2.exs b/challenge-283/packy-anderson/elixir/ch-2.exs
new file mode 100755
index 0000000000..82b3fd72ac
--- /dev/null
+++ b/challenge-283/packy-anderson/elixir/ch-2.exs
@@ -0,0 +1,77 @@
+#!/usr/bin/env elixir
+
+defmodule PWC do
+  @doc """
+  Helper function that accepts a list and generates a Multiset/
+  Bag implemented as a Map.
+
+  https://en.wikipedia.org/wiki/Multiset
+  """
+  def makeBag(list) do
+    {_, bag} = Enum.map_reduce(list, %{}, fn i, bag ->
+      { i, Map.put(bag, i, Map.get(bag, i, 0) + 1) }
+    end)
+    bag
+  end
+
+  @doc """
+  Return true if for every index i in the range 0 <= i < size
+  of array, the digit i occurs exactly the $ints[$i] times in
+  the given array, otherwise return false.
+  """
+  def digitCountValue(ints) do
+    bag = makeBag(ints)
+    results = Enum.map(0 .. length(ints)-1, fn i ->
+      # return a tuple of {digit, occurrences, expected}
+      { i, Map.get(bag, i, 0), Enum.at(ints, i) }
+    end)
+    explain = Enum.map(results, fn tuple ->
+      digit  = elem(tuple, 0)
+      occurs = elem(tuple, 1)
+      times  = elem(tuple, 2)
+      otimes = cond do
+        occurs == 0 -> "0 times"
+        occurs >= 2 -> "#{occurs} times"
+        true        -> "1 time"
+      end
+      ttimes = cond do
+        times == 0 -> "0 times"
+        times >= 2 -> "#{times} times"
+        true       -> "1 time"
+      end
+      if occurs == times do
+        "$ints[#{digit}] = #{times}, the digit #{digit} " <>
+        "occurs #{otimes}"
+      else
+        "$ints[#{digit}] = #{times}, the digit #{digit} " <>
+        "occurs #{otimes} rather than #{ttimes}"
+      end
+    end)
+    |> Enum.join("\n")
+    passes = Enum.all?(results, fn tuple ->
+      elem(tuple, 1) == elem(tuple, 2)
+    end)
+    |> to_string
+    {passes, explain}
+  end
+
+  @doc """
+  Function to print the input, invoke the solution code,
+  and print the output.
+  """
+  def solution(ints) do
+    IO.puts("Input: @ints = (" <> Enum.join(ints, ", ") <> ")")
+    {passes, explain} = digitCountValue(ints)
+    IO.puts("Output: " <> passes)
+    IO.puts("\n" <> explain)
+  end
+end
+
+IO.puts("Example 1:")
+PWC.solution([1, 2, 1, 0])
+
+IO.puts("\nExample 2:")
+PWC.solution([0, 3, 0])
+
+IO.puts("\nExample 3:")
+PWC.solution([0, 1, 2, 2])