Function invertTree

javascript/0226-invert-binary-tree.js:7–12

(root)

 * @return {TreeNode}
 */
var invertTree = (root) => {
    const isBaseCase = root === null;
    if (isBaseCase) return root;

    return dfs(root);
};

const dfs = (root) => {
    const left = invertTree(root.left);