[LeetCode] 662. Maximum Width of Binary Tree

void wbtHelp(vector<int> &lf,int idx,unsigned int lev,int &maxwid,TreeNode *r){if(r==NULL) return;if(lev+1>lf.size()) lf.push_back(idx);else maxwid=max(maxwid,idx+1-lf[lev]);wbtHelp(lf,2*idx,lev+1,maxwid,r->left);wbtHelp(lf,2*idx+1,lev+1,maxwid,r->right);}int widthOfBinaryTree(TreeNode* root){vector<int> lf;int maxwid=1;wbtHelp(lf,1,0,maxwid,root);return maxwid;}