776. Split BST
class Solution {
public:
vector<TreeNode*> splitBST(TreeNode* root, int V) {
vector<TreeNode *> res(2, NULL);
if(root == NULL) return res;
if(root->val > V){
res[1] = root;
auto res1 = splitBST(root->left, V);
root->left = res1[1];
res[0]=res1[0];
}else{
res[0] = root;
auto res1 = splitBST(root->right, V);
root->right = res1[0];
res[1] = res1[1];
}
return res;
}
};