c++ solution|| O(N) || 100.00% faster
So I am calling at every node and asking total sum and total number of node including that node itself so every subtree will return total sum of tree and total 
So I am calling at every node and asking total sum and total number of node including that node itself so every subtree will return total sum of tree and total number of node. gobal variable will keep updating.\n```\nint count=0;\npair<int,int> valueSum(TreeNode* root){\n\tif(root==NULL) return {0,0};\n\tauto left=valueSum(root->left);\n\tauto right=valueSum(root->right);\n\tint sum=(left.first+right.first+root->val);\n\tint n=(left.second+right.second+1);        \n\tcount+=((sum/n)==root->val);\n\treturn {sum,n};\n}\nint averageOfSubtree(TreeNode* root) {\n\tauto p1=valueSum(root);\n\treturn count;\n}\n```
['Recursion', 'C']