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.

算法解析：既可以用深度优先搜索，也可以用广度优先搜索，前者可以节省代码，后者可以提高速度，但两个方法都不会超时。

C语言版

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     struct TreeNode *left; *     struct TreeNode *right; * }; */int maxDepth(struct TreeNode* root) {       if(root)    {        root->val = 0;        root->val = maxDepth(root->left) + 1;        int depth = maxDepth(root->right) + 1;        if(root->val < depth)            root->val = depth;        return root->val;    }    else        return 0;}

Python版（深度优先搜索）

# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def maxDepth(self, root):        """        :type root: TreeNode        :rtype: int        """        if root:            root.val = 0            root.val = self.maxDepth(root.left) + 1            depth = self.maxDepth(root.right) + 1            if root.val < depth:                root.val = depth            return root.val        else:            return 0

Python版（更Pythonic的代码，别人写的）

class Solution:    def maxDepth(self, root):        """        :type root: TreeNode        :rtype: int        """        if not root:            return 0        return max(self.maxDepth(root.left), self.maxDepth(root.right)) + 1