Data commit

Task/Zebra-puzzle/Elixir/zebra-puzzle.elixir

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+defmodule ZebraPuzzle do
+  defp adjacent?(n,i,g,e) do
+    Enum.any?(0..3, fn x ->
+      (Enum.at(n,x)==i and Enum.at(g,x+1)==e) or (Enum.at(n,x+1)==i and Enum.at(g,x)==e)
+    end)
+  end
+
+  defp leftof?(n,i,g,e) do
+    Enum.any?(0..3, fn x -> Enum.at(n,x)==i and Enum.at(g,x+1)==e end)
+  end
+
+  defp coincident?(n,i,g,e) do
+    Enum.with_index(n) |> Enum.any?(fn {x,idx} -> x==i and Enum.at(g,idx)==e end)
+  end
+
+  def solve(content) do
+    colours = permutation(content[:Colour])
+    pets    = permutation(content[:Pet])
+    drinks  = permutation(content[:Drink])
+    smokes  = permutation(content[:Smoke])
+    Enum.each(permutation(content[:Nationality]), fn nation ->
+      if hd(nation) == :Norwegian, do:                                      # 10
+        Enum.each(colours, fn colour ->
+          if leftof?(colour, :Green, colour, :White)      and               # 5
+             coincident?(nation, :English, colour, :Red)  and               # 2
+             adjacent?(nation, :Norwegian, colour, :Blue), do:              # 15
+            Enum.each(pets, fn pet ->
+              if coincident?(nation, :Swedish, pet, :Dog), do:              # 3
+                Enum.each(drinks, fn drink ->
+                  if Enum.at(drink,2) == :Milk                   and        # 9
+                     coincident?(nation, :Danish, drink, :Tea)   and        # 4
+                     coincident?(colour, :Green, drink, :Coffee), do:       # 6
+                    Enum.each(smokes, fn smoke ->
+                      if coincident?(smoke, :PallMall, pet, :Birds)    and  # 7
+                         coincident?(smoke, :Dunhill, colour, :Yellow) and  # 8
+                         coincident?(smoke, :BlueMaster, drink, :Beer) and  # 13
+                         coincident?(smoke, :Prince, nation, :German)  and  # 14
+                         adjacent?(smoke, :Blend, pet, :Cats)          and  # 11
+                         adjacent?(smoke, :Blend, drink, :Water)       and  # 16
+                         adjacent?(smoke, :Dunhill, pet, :Horse), do:       # 12
+                        print_out(content, transpose([nation, colour, pet, drink, smoke]))
+    end)end)end)end)end)
+  end
+
+  defp permutation([]), do: [[]]
+  defp permutation(list) do
+    for x <- list, y <- permutation(list -- [x]), do: [x|y]
+  end
+
+  defp transpose(lists) do
+    List.zip(lists) |> Enum.map(&Tuple.to_list/1)
+  end
+
+  defp print_out(content, result) do
+    width = for {k,v}<-content, do: Enum.map([k|v], &length(to_char_list &1)) |> Enum.max
+    fmt = Enum.map_join(width, " ", fn w -> "~-#{w}s" end) <> "~n"
+    nation = Enum.find(result, fn x -> :Zebra in x end) |> hd
+    IO.puts "The Zebra is owned by the man who is #{nation}\n"
+    :io.format fmt, Keyword.keys(content)
+    :io.format fmt, Enum.map(width, fn w -> String.duplicate("-", w) end)
+    fmt2 = String.replace(fmt, "s", "w", global: false)
+    Enum.with_index(result)
+    |> Enum.each(fn {x,i} -> :io.format fmt2, [i+1 | x] end)
+  end
+end
+
+content = [ House:       '',
+            Nationality: ~w[English Swedish Danish Norwegian German]a,
+            Colour:      ~w[Red Green White Blue Yellow]a,
+            Pet:         ~w[Dog Birds Cats Horse Zebra]a,
+            Drink:       ~w[Tea Coffee Milk Beer Water]a,
+            Smoke:       ~w[PallMall Dunhill BlueMaster Prince Blend]a ]
+
+ZebraPuzzle.solve(content)