Data commit

Task/Levenshtein-distance/Elixir/levenshtein-distance.elixir

@@ -0,0 +1,28 @@
+defmodule Levenshtein do
+  def distance(a, b) do
+    ta = String.downcase(a) |> to_charlist |> List.to_tuple
+    tb = String.downcase(b) |> to_charlist |> List.to_tuple
+    m = tuple_size(ta)
+    n = tuple_size(tb)
+    costs = Enum.reduce(0..m, %{},   fn i,acc -> Map.put(acc, {i,0}, i) end)
+    costs = Enum.reduce(0..n, costs, fn j,acc -> Map.put(acc, {0,j}, j) end)
+    Enum.reduce(0..n-1, costs, fn j, acc ->
+      Enum.reduce(0..m-1, acc, fn i, map ->
+        d = if elem(ta, i) == elem(tb, j) do
+              map[ {i,j} ]
+            else
+              Enum.min([ map[ {i  , j+1} ] + 1,         # deletion
+                         map[ {i+1, j  } ] + 1,         # insertion
+                         map[ {i  , j  } ] + 1 ])       # substitution
+            end
+        Map.put(map, {i+1, j+1}, d)
+      end)
+    end)
+    |> Map.get({m,n})
+  end
+end
+
+words = ~w(kitten sitting saturday sunday rosettacode raisethysword)
+Enum.each(Enum.chunk(words, 2), fn [a,b] ->
+  IO.puts "distance(#{a}, #{b}) = #{Levenshtein.distance(a,b)}"
+end)