1 class Solution 2 { 3     public: 4         int rangeSumBST(TreeNode* root, int L, int R) 5         { 6             int result = 0; 7             if(root->left) 8                 result += rangeSumBST(root->left, L, R); 9             if(root->right)10                 result += rangeSumBST(root->right, L, R);11             12             if(root->val>=L && root->val<=R)13                 result += root->val;14             15             return result;16         }17 };