LeetCode 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 {    vector<TreeNode*>low;    vector<TreeNode*>high;    int level;public:    int maxDepth(TreeNode* root) {        level=0;        if(root==NULL) return 0;        high.push_back(root);        low.clear();        while(!high.empty()){            level++;            for(int i=0;i<high.size();i++){                if(high[i]->left) low.push_back(high[i]->left);                if(high[i]->right) low.push_back(high[i]->right);            }            high=low;            low.clear();        }        return level;    }};

递归方式：

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