LeetCode 剑指offer 面试题55 - I. 二叉树的深度

/**
 * 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) {
        if(!root) return 0;
        return dfs(root,1);
    }
    int dfs(TreeNode* root,int depth)
    {
        if(!root->left&&!root->right) return depth;
        else if(!root->left&&root->right) return dfs(root->right,depth+1);
        else if(!root->right&&root->left) return dfs(root->left,depth+1);
        else return max(dfs(root->left,depth+1),dfs(root->right,depth+1));
    }
};