leetcode - Maximum Depth of Binary Tree

题目描述：点击此处

/**
 * 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 maxInt(int a, int b){
    return a >= b ? a : b;
  }
  int maxDepth(TreeNode *root) {
    // Start typing your C/C++ solution below
    // DO NOT write int main() function
    if (root == NULL)
      return 0;
    return maxInt(maxDepth(root->left),maxDepth( root->right)) + 1;
  }
};