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.
题目大意：
给一颗二叉树，求最大深度。
解题方法：
1.利用递归遍历二叉树。
注意事项：
C++代码：
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int maxDepth(TreeNode* root)
{
int l,r;
if(root==nullptr) return ;
l=maxDepth(root->left);
r=maxDepth(root->right);
return l>r?l+:r+;
}
};