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.
题解： 题意比较清楚， 找到从root出发最长的一条路径的长度。 采用DFS即可。
相似的一道题： Minimux Depth of Binary Tree 解法： http://www.cnblogs.com/double-win/p/3737237.html
/**
* 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 minDepth(TreeNode *root) {
if(root==NULL) return ;
if(root->left==NULL && root->right==NULL) return ; int Leftdepth = minDepth(root->left);
int Rightdepth = minDepth(root->right); if(Leftdepth==)
return Rightdepth+;
else if(Rightdepth==)
return Leftdepth+; return min(Leftdepth,Rightdepth)+;
}
};