September 2017 Update

Task/Permutations/Ruby/permutations-2.rb

@@ -1,37 +0,0 @@
-class Array
-  # Yields distinct permutations of _self_ to the block.
-  # This method requires that all array elements be Comparable.
-  def distinct_permutation  # :yields: _ary_
-    # If no block, return an enumerator. Works with Ruby 1.8.7.
-    block_given? or return enum_for(:distinct_permutation)
-
-    copy = self.sort
-    yield copy.dup
-    return if size < 2
-
-    while true
-      # from: "The Art of Computer Programming" by Donald Knuth
-      j = size - 2;
-      j -= 1 while j > 0 && copy[j] >= copy[j+1]
-      if copy[j] < copy[j+1]
-        l = size - 1
-        l -= 1 while copy[j] >= copy[l]
-        copy[j] , copy[l] = copy[l] , copy[j]
-        copy[j+1..-1] = copy[j+1..-1].reverse
-        yield copy.dup
-      else
-        break
-      end
-    end
-  end
-end
-
-permutations = []
-[1,1,2].distinct_permutation do |p| permutations << p end
-p permutations
-# => [[1, 1, 2], [1, 2, 1], [2, 1, 1]]
-
-if RUBY_VERSION >= "1.8.7"
-  p [1,1,2].distinct_permutation.to_a
-  # => [[1, 1, 2], [1, 2, 1], [2, 1, 1]]
-end