[LeetCode] 637. Average of Levels in Binary Tree

void aveLevHelp(vector<double> &res,vector<int> &cnt,unsigned int lev,TreeNode *r){if(r==NULL) return;if(lev+1>res.size()){res.push_back(0);cnt.push_back(0);}res[lev]+=r->val;cnt[lev]++;aveLevHelp(res,cnt,lev+1,r->left);aveLevHelp(res,cnt,lev+1,r->right);}vector<double> averageOfLevels(TreeNode* r){vector<double> res;vector<int> cnt;aveLevHelp(res,cnt,0,r);for(unsigned int i=0;i<res.size();++i){res[i]/=cnt[i];}return res;}