Cousins in Binary Tree

import { TreeNode } from '@algorithm/lib';
 
export function isCousins(root: TreeNode | null, x: number, y: number): boolean {
  if (!root) {
    return false;
  }
 
  const cousins = {
    [x]: { depth: -1, parent: -1 },
    [y]: { depth: -1, parent: -1 },
  };
 
  const dfs = (node: TreeNode, parentNode: TreeNode | null = null, depth = 0) => {
    if (node.val === x || node.val == y) {
      cousins[node.val] = { depth, parent: parentNode ? parentNode.val : -1 };
    }
    node.left && dfs(node.left, node, depth + 1);
    node.right && dfs(node.right, node, depth + 1);
  };
  dfs(root);
 
  return cousins[x].depth === cousins[y].depth && cousins[x].parent !== cousins[y].parent;
}