1123.js

/** ------------------------------------------------------------------------------
 * 
 * 1123. Lowest Common Ancestor of Deepest Leaves
 * Topics: Tree, DFS
 * https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/?envType=daily-question&envId=2025-04-04
 * 
 ------------------------------------------------------------------------------ */
const maxDepth = (d = (n) => (n ? 1 + Math.max(d(n.left), d(n.right)) : 0))

/**
 * @param {TreeNode} root
 * @return {TreeNode}
 */
var lcaDeepestLeaves = function (root) {
  const [depthLeft, depthRight] = [maxDepth(root.left), maxDepth(root.right)]
  if (depthLeft === depthRight) {
    return root
  }
  return lcaDeepestLeaves(depthLeft > depthRight ? root.left : root.right)
}

console.log(lcaDeepestLeaves([3, 5, 1, 6, 2, 0, 8, null, null, 7, 4]))