LeetCode 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.

分析：

这道题要求二叉树的最大深度，那么考虑递归实现，求左右分支中较大的那个深度，然后加上1（即root这一层）即可。

/**
 * 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) {
        return 0;
    }
    return Math.max(maxDepth(root.left),maxDepth(root.right)) + 1;
};