Data commit

Task/Move-to-front-algorithm/Ruby/move-to-front-algorithm.rb

@@ -0,0 +1,30 @@
+module MoveToFront
+
+  ABC = ("a".."z").to_a.freeze
+
+  def self.encode(str)
+    ar = ABC.dup
+    str.chars.each_with_object([]) do |char, memo|
+      memo << (i = ar.index(char))
+      ar = m2f(ar,i)
+    end
+  end
+
+  def self.decode(indices)
+    ar = ABC.dup
+    indices.each_with_object("") do |i, str|
+      str << ar[i]
+      ar = m2f(ar,i)
+    end
+  end
+
+  private
+  def self.m2f(ar,i)
+    [ar.delete_at(i)] + ar
+  end
+
+end
+
+['broood', 'bananaaa', 'hiphophiphop'].each do |word|
+  p word == MoveToFront.decode(p MoveToFront.encode(p word))
+end