LintCode 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
        return depth(root);
    }
    int depth(TreeNode *node)
    {
        if(node==NULL)
            return 0;
        int left=depth(node->left);
        int right=depth(node->right);
        return max(left,right)+1;
    }
};