title: Get key from value - Dictionary<string, List<string>>
body: <p>I am having trouble getting the key by specifying a value. What is the best way I can achieve this?</p>
  
  <pre><code>var st1= new List&lt;string&gt; { "NY", "CT", "ME" };
  var st2= new List&lt;string&gt; { "KY", "TN", "SC" };
  var st3= new List&lt;string&gt; { "TX", "OK", "MO" };
  var statesToEmailDictionary = new Dictionary&lt;string, List&lt;string&gt;&gt;();
  statesToEmailDictionary.Add("test1@gmail.com", st1);
  statesToEmailDictionary.Add("test2@gmail.com", st2);
  statesToEmailDictionary.Add("test3@gmail.com", st3);
  
  var emailAdd = statesToEmailDictionary.FirstOrDefault(x =&gt; x.Value.Where(y =&gt; y.Contains(state))).Key;
  </code></pre>