title: Find max and min key in associative array
body: <p>I have associative array like </p>
  
  <pre><code>array
  {
      [company 1]=&gt;array
                        (
                          [1981] =&gt; 1
                          [1945] =&gt; 3
                        )
     [company 2]=&gt;array
                      (
                         [1990] =&gt; 18
                         [2005] =&gt; 13
                      )
     [company 3]=&gt;array
                      (
                         [1950] =&gt; 6
                         [2012] =&gt; 9
                      )
  }
  </code></pre>
  
  <p>I want to get lowest and highest key i.e. 1945 and 2012.
  How can i achieve this? I have already searched over stackoverflow and <a href="https://stackoverflow.com/questions/5093171/hightest-value-of-an-associative-array">Hightest value of an associative array</a>  is the nearest possibility but it gives out min and max value and I want min and max key.</p>
  
  <p>**I don't want to use foreach loop **</p>