title: Set vertex of vector<vector<int>> to 0, 0
body: <p>I've got a <code>std::vector&lt;std::vector&lt;int &gt; &gt;</code> built from a <code>std::vector&lt;std::string&gt;</code> read in from a file. I am successful in using it to perform a BFS, however I have one little catch:</p>
  
  <p>How can I set the lower-left corner of the <code>std::vector&lt;std::vector&lt;int&gt; &gt;</code> to <code>(0,0)</code> before I perform by BFS?</p>