09-Maximum-Depth-Of-Binary-Tree-LC-104.js

/*
104. Maximum Depth of Binary Tree
Easy

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.
Note: A leaf is a node with no children.

Example:
Given binary tree [3,9,20,null,null,15,7],
    3
   / \
  9  20
    /  \
   15   7

return its depth = 3.
*/

/**
 * 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 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
};