[LeetCode]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.

思考：DFS。

/**

 * 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 DFS(TreeNode *root)

    {

        if(root)

        {

            return max(DFS(root->left),DFS(root->right))+1;

        }

        else return 0;

    }

    int maxDepth(TreeNode *root) {

        return DFS(root);

    }

};