104. Maximum Depth of Binary Tree

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode* root) {
        int dep = 0;
        if (root == NULL) return 0;
        dep = max(maxDepth(root->left) + 1, maxDepth(root->right) + 1);
        return dep;
    }
};