title: Using std::sort to sort Matrix
body: <p>Is there a way I can sort matrix elements with the sort function from std?</p>
  
  <pre><code>//Using this matrix
  vector&lt;vector&lt;string&gt;&gt; mat;
  </code></pre>
  
  <p>For example if you have </p>
  
  <pre><code>5 2 1
  0 0 2
  1 4 3
  </code></pre>
  
  <p>The result would be </p>
  
  <pre><code>0 0 1
  1 2 2
  3 4 5
  </code></pre>