LintCode-剑指Offer-(97)二叉树的最大深度

/** * Definition of TreeNode: * class TreeNode { * public: *     int val; *     TreeNode *left, *right; *     TreeNode(int val) { *         this->val = val; *         this->left = this->right = NULL; *     } * } */class Solution {public:    /**    * @param root: The root of binary tree.    * @return: An integer    */    int maxDepth(TreeNode *root) {        // write your code here        maxD(root,1);        return maxdepth;    }    int maxdepth = 0;    void maxD(TreeNode* node,int d){        if (node==NULL)return;        if (maxdepth<d)maxdepth = d;        maxD(node->left,d+1);        maxD(node->right,d+1);    }};