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.

相对于求最小值而言，求最大值就更简单了。直接递归就可以了。

/**
* Definition for binary tree
* 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 == NULL)
return 0;
int left_max = maxDepth(root->left);
int right_max = maxDepth(root->right);
return (left_max > right_max ? left_max : right_max) + 1;
}
};