Function dfs

javascript/0872-leaf-similar-trees.js:18–27

(node, arr)

 */
var leafSimilar = function (root1, root2) {
    const dfs = (node, arr) => {
        if (!node.left && !node.right) {
            arr.push(node.val);
            return arr;
        }
        if (node.left) dfs(node.left, arr);
        if (node.right) dfs(node.right, arr);

        return arr;
    };

    const arr1 = dfs(root1, []);
    const arr2 = dfs(root2, []);