<p>Given an integer <code>n</code>, return <em>a list of all possible <strong>full binary trees</strong> with</em> <code>n</code> <em>nodes</em>. Each node of each tree in the answer must have <code>Node.val == 0</code>.</p> <p>Each element of the answer is the root node of one possible tree. You may return the final list of trees in <strong>any order</strong>.</p> <p>A <strong>full binary tree</strong> is a binary tree where each node has exactly <code>0</code> or <code>2</code> children.</p> <p> </p> <p><strong>Example 1:</strong></p> <img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/08/22/fivetrees.png" style="width: 700px; height: 400px;" /> <pre> <strong>Input:</strong> n = 7 <strong>Output:</strong> [[0,0,0,null,null,0,0,null,null,0,0],[0,0,0,null,null,0,0,0,0],[0,0,0,0,0,0,0],[0,0,0,0,0,null,null,null,null,0,0],[0,0,0,0,0,null,null,0,0]] </pre> <p><strong>Example 2:</strong></p> <pre> <strong>Input:</strong> n = 3 <strong>Output:</strong> [[0,0,0]] </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= n <= 20</code></li> </ul>