LintCode-劍指Offer-(97)二叉樹的最大深度

/**
 * 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);
    }

};