* Definition for a binary tree node.
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
int rangeSumBST(TreeNode* root, int L, int R) {
if(root->val >= L && root->val <=R)
return root->val + rangeSumBST(root->left,L,R) + rangeSumBST(root->right,L,R);
return rangeSumBST(root->left,L,R) + rangeSumBST(root->right,L,R);