Function rangeSumBST

javascript/0938-range-sum-of-bst.js:19–30

(root, low, high)

 * @return {number}
 */
var rangeSumBST = function (root, low, high) {
    let total = 0;

    const dfs = (node) => {
        if (!node) return;
        if (node.val >= low && node.val <= high) total += node.val;
        dfs(node.left);
        dfs(node.right);
    };
    dfs(root);
    return total;
};