097. 二叉树的最大深度.cpp

/**
 * 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:
    int maxDepth(TreeNode *root) 
    {
        if(root==NULL)
            return 0;
        return max(maxDepth(root->left),maxDepth(root->right))+1;
    }
};