class="language-c++ highlighter-rouge"><span class="n">ListNode</span></code>s (i.e. no calls to <code class="language-c++ highlighter-rouge"><span class="k">new</span></code> or <code class="language-c++ highlighter-rouge"><span class="k">delete</span></code>).  Do not replace/swap the <code class="language-c++ highlighter-rouge"><span class="n">ListNode</span></code> data values. You may declare <code class="language-c++ highlighter-rouge"><span class="n">ListNode</span><span class="o">*</span></code> poi