Create 669. Trim a Binary Search Tree.cpp

Author: fengvyi

C++/669. Trim a Binary Search Tree.cpp

@@ -0,0 +1,19 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    TreeNode* trimBST(TreeNode* root, int L, int R) {
+        while(root && (root->val < L || root->val > R)) root = root->val < L ? root->right : root->left;
+        if(!root) return NULL;
+        root->left = trimBST(root->left, L, R);
+        root->right = trimBST(root->right, L, R);
+        return root;
+    }
+};