Add hash solution

DIRECTORY.md

@@ -24,7 +24,6 @@
       * [Anagram Checker](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/anagram_checker.rb)
       * [Jewels And Stones](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/jewels_and_stones.rb)
       * [Remove Vowels](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/remove_vowels.rb)
-      * [Uncommon Words](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/strings/uncommon_words.rb)
     * [Two Sum](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/two_sum.rb)
     * [Two Sum Ii](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/arrays/two_sum_ii.rb)
   * Binary Trees
@@ -36,6 +35,7 @@
     * [Find All Duplicates In An Array](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/hash_table/find_all_duplicates_in_an_array.rb)
     * [Richest Customer Wealth](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/hash_table/richest_customer_wealth.rb)
     * [Two Sum](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/hash_table/two_sum.rb)
+    * [Uncommon Words](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/hash_table/uncommon_words.rb)
   * Linked Lists
     * [Circular Linked List](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/linked_lists/circular_linked_list.rb)
     * [Doubly Linked List](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/linked_lists/doubly_linked_list.rb)

data_structures/hash_table/uncommon_words.rb

@@ -16,4 +16,33 @@
 #
 # Example 2:
 # Input: A = "apple apple", B = "banana"
-# Output: ["banana"]
+# Output: ["banana"]
+
+#
+# Approach 1: Hash
+#
+# Time Complexitiy: O(n)
+
+def find_uncommon_words(strA, strB)
+  array = strA.concat(" ", strB).split(" ")
+  hash = Hash.new(0)
+  result = []
+
+  array.each do |word|
+    if hash[word]
+      hash[word] += 1
+    else
+      hash[word] = 1
+    end
+  end
+
+  hash.each do |k, v|
+    if v < 2
+      result.push(k)
+    end
+  end
+
+  result
+end
+
+puts find_uncommon_words("this apple is sweet", "this apple is sour")