【Maximum Depth of Binary Tree 】cpp

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 0;
            if ( !root->left && !root->right ) return 1;
            return std::max(Solution::maxDepth(root->left)+1, Solution::maxDepth(root->right)+1);
    }
};

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 0;
            return max(Solution::maxDepth(root->left), Solution::maxDepth(root->right))+1;
    }
};