104-easy-Maximum_Depth_of_Binary_Tree.js

/**
104. Maximum Depth of Binary Tree

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
 */

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function(root) {
  if (root === null) {
    return 0;
  }
  return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1;
};