Merge pull request #149 from jsca-kwok/jk-uncommon-words

Uncommon words algorithm

DIRECTORY.md

@@ -55,6 +55,7 @@
     * [Good Pairs](https://github.com/TheAlgorithms/Ruby/blob/master/data_structures/hash_table/good_pairs.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

@@ -0,0 +1,48 @@
+# Challenge name: Uncommon words from two sentences
+#
+# We are given two sentences A and B.
+# (A sentence is a string of space separated words.
+# Each word consists only of lowercase letters.)
+#
+# A word is uncommon if it appears exactly once in one of the sentences,
+# and does not appear in the other sentence.
+#
+# Return a list of all uncommon words.
+# You may return the list in any order.
+#
+# Example 1:
+# Input: A = "this apple is sweet", B = "this apple is sour"
+# Output: ["sweet","sour"]
+#
+# Example 2:
+# Input: A = "apple apple", B = "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|
+    hash[word] += 1
+  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")
+# => ["sweet", "sour"]
+
+puts find_uncommon_words("apple apple", "banana")
+# => ["banana"]