Comment body goes here.
void helper(TreeNode* root, int level,vector& ans)
{
if(root==NULL)
return;
ans[level] = ans[level] + root->val;
helper(root->left,level+1,ans);
helper(root->right,level+1,ans);
}
int Solution::solve(TreeNode* root) {
vector<int> ans(500,0);
helper(root,1,ans);
return *max_element(ans.begin(),ans.end());
}