title: All possible combinations from given sets but without repetition of sets’ internal elements
body: <p>I have some fixed sets of integers, with distict increasing values in each a set, for example: </p>
  
  <pre><code>{1, 2, 4}, {1, 3}, {2, 4}, {2, 7}, {3, 6}, {5, 6}, {3, 5, 7}.
  </code></pre>
  
  <p>Is there any algorithm or better C# code, generating all possible combinations from given sets but <strong>without repetition of their internal integers</strong>, i.e.</p>
  
  <pre><code>[{1, 2, 4}, {3, 6}] &lt; all integers are unique
  
  [{1, 2, 4}, {3, 5, 7}] &lt; all integers are unique
  
  [{1, 3}, {2, 4}, {5, 6}] &lt;– all integers are unique.
  </code></pre>
  
  <p>and so on.</p>
  
  <p>====================================</p>
  
  <p>Here is possible organization of input data:</p>
  
  <pre><code>        var set1 = new HashSet&lt;int&gt;() { 1, 2, 4 };
          var set2 = new HashSet&lt;int&gt;() { 1, 3 };
          var set3 = new HashSet&lt;int&gt;() { 2, 4 };
          var set4 = new HashSet&lt;int&gt;() { 2, 7 };
          var set5 = new HashSet&lt;int&gt;() { 3, 6 };
          var set6 = new HashSet&lt;int&gt;() { 5, 6 };
          var set7 = new HashSet&lt;int&gt;() { 3, 5, 7 };
  
          var inputList = new List&lt;HashSet&lt;int&gt;&gt;();
          inputList.Add(set1);
          inputList.Add(set2);
          inputList.Add(set3);
          inputList.Add(set4);
          inputList.Add(set5);
          inputList.Add(set6);
          inputList.Add(set7);
  </code></pre>
  
  <p>I need to obtain a list (or collection) of all possible lists (i.e. combinations) of sets from inputList with unique integers in each internal list (combination).</p>
  
  <hr>
  
  <p>This question was marked as duplicate and as a question which already has an answer here:
  “Generating all Possible Combinations (8 answers)”. However, to my mind, it is essentially a <strong>DIFFERENT</strong> question:</p>
  
  <ul>
  <li><p>input data are not two arrays of the same length but rather a list of sets with different number of elements in each a set;</p></li>
  <li><p>equal elements may be present in different sets.</p></li>
  </ul>