class Solution { public: /* int maxDepth(TreeNode* root) { // write code here if(!root) return 0; queue<TreeNode*> q; q.push(root); int hight=0; while(!q.empty()) { ++hight; int n = q.size(); for(int i=0;i<n;++i) { TreeNode* temp = q.front(); q.pop(); if(temp->left) q.push(temp->left); if(temp->right) q.push(temp->right); } } return hight; }*/ int maxDepth(TreeNode* root) { if(root == nullptr) return 0; int left_hight = maxDepth(root->left) + 1; int right_hight = maxDepth(root->right)+1; return left_hight > right_hight ? left_hight : right_hight; } };