题目：
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.
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) {
if (!root) return ;
if ( !root->left && !root->right ) return ;
return std::max(Solution::maxDepth(root->left)+, Solution::maxDepth(root->right)+);
}
};
tips：
比求最小叶子节点深度容易一些。
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第二次过这道题，一次AC。
/**
* 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) {
if ( !root ) return ;
return max(Solution::maxDepth(root->left), Solution::maxDepth(root->right))+;
}
};