<p>Given the <code>root</code> node of a binary search tree and two integers <code>low</code> and <code>high</code>, return <em>the sum of values of all nodes with a value in the <strong>inclusive</strong> range </em><code>[low, high]</code>.</p> <p> </p> <p><strong class="example">Example 1:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/bst1.jpg" style="width: 400px; height: 222px;" /> <pre> <strong>Input:</strong> root = [10,5,15,3,7,null,18], low = 7, high = 15 <strong>Output:</strong> 32 <strong>Explanation:</strong> Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32. </pre> <p><strong class="example">Example 2:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2020/11/05/bst2.jpg" style="width: 400px; height: 335px;" /> <pre> <strong>Input:</strong> root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10 <strong>Output:</strong> 23 <strong>Explanation:</strong> Nodes 6, 7, and 10 are in the range [6, 10]. 6 + 7 + 10 = 23. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li>The number of nodes in the tree is in the range <code>[1, 2 * 10<sup>4</sup>]</code>.</li> <li><code>1 <= Node.val <= 10<sup>5</sup></code></li> <li><code>1 <= low <= high <= 10<sup>5</sup></code></li> <li>All <code>Node.val</code> are <strong>unique</strong>.</li> </ul>