Function dfs

javascript/0337-house-robber-iii.js:16–27

(root)

 */
var rob = function (root) {
    function dfs(root) {
        if (!root) return [0, 0];

        const leftSubTree = dfs(root.left);
        const rightSubTree = dfs(root.right);

        const withoutRoot =
            Math.max(...leftSubTree) + Math.max(...rightSubTree);
        const withRoot = root.val + leftSubTree[0] + rightSubTree[0];

        return [withoutRoot, withRoot];
    }

    return Math.max(...dfs(root));
};