title: array of substrings in array of strings
body: <p>I have two array of strings. Strings in one array might be the subset of string in other array. I need to find out which all strings in one array are the substrings of strings in the other array</p>
  
  <p>Example:</p>
  
  <pre><code>arr1 = ["firestorm", "peanut", "earthworm"]
  arr2 = ["fire", "tree", "worm", "rest"]
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>res = ["fire","worm", "rest"]
  </code></pre>
  
  <p>My solution is mentioned below. But it takes a lot of time. I have to process Thousands of words.</p>
  
  <p>Solution:</p>
  
  <pre><code>res =[]
  arr1.each do |word1|
    arr2.each do |word2|
     if word1.include? word2
       res &lt;&lt; word2
     end
    end
  end
  </code></pre>
  
  <p>Please suggest me the faster way to to do this</p>