1function TreeNode(val, left, right) {
2    this.val = (val===undefined ? 0 : val)
3    this.left = (left===undefined ? null : left)
4    this.right = (right===undefined ? null : right)
5}
6
7var subtreeWithAllDeepest = function(root) {
8    const dfs = (node) => {
9        if (!node) return {node: null, depth: 0};
10        const left = dfs(node.left);
11        const right = dfs(node.right);
12        if (left.depth > right.depth) return {node: left.node, depth: left.depth + 1};
13        if (right.depth > left.depth) return {node: right.node, depth: right.depth + 1};
14        return {node: node, depth: left.depth + 1};
15    };
16    return dfs(root).node;
17};