Just another update

Task/Remove-duplicate-elements/Ruby/remove-duplicate-elements-2.rb

@@ -0,0 +1,26 @@
+class Array
+  # used Hash
+  def uniq1
+    each_with_object({}) {|elem, h| h[elem] = true}.keys
+  end
+  # sort (requires comparable)
+  def uniq2
+    sorted = sort
+    pre = sorted.first
+    sorted.each_with_object([pre]){|elem, uniq| uniq << (pre = elem) if elem != pre}
+  end
+  # go through the list
+  def uniq3
+    each_with_object([]) {|elem, uniq| uniq << elem unless uniq.include?(elem)}
+  end
+end
+
+ary = [1,1,2,1,'redundant',[1,2,3],[1,2,3],'redundant']
+p ary.uniq1             #=> [1, 2, "redundant", [1, 2, 3]]
+p ary.uniq2 rescue nil  #   Error (not comparable)
+p ary.uniq3             #=> [1, 2, "redundant", [1, 2, 3]]
+
+ary = [1,2,3,7,6,5,2,3,4,5,6,1,1,1]
+p ary.uniq1             #=> [1, 2, 3, 7, 6, 5, 4]
+p ary.uniq2             #=> [1, 2, 3, 4, 5, 6, 7]
+p ary.uniq3             #=> [1, 2, 3, 7, 6, 5, 4]