title: find all common part between vector
body: <p>I have n vectors with unique integers. I want to find all the common part between them. Is there any specific algorithm or data struct for this problem?</p>
  <p>example:</p>
  <pre><code>std::vector&lt;int&gt; a = {0,1,2,3,4,5,6,7,8,9,10,11,12,13};
  std::vector&lt;int&gt; b = {1,7,8,9,2,10,11,12};
  std::vector&lt;int&gt; c = {4,9,8,7,0,1,2,3};
  </code></pre>
  <p>result:
  ignore result with only one interge</p>
  <p>7,8,9 between a and b</p>
  <p>10,11,12 bewteen a and b</p>
  <p>0,1,2,3 between a and c</p>