Add prompt for LC 669 Trim a BST

Author: timothyshores

669. Trim a Binary Search Tree.js

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+/*
+
+Given the root of a binary search tree and the lowest and highest boundaries as low and high, trim the tree so that all its elements lies in [low, high]. Trimming the tree should not change the relative structure of the elements that will remain in the tree (i.e., any node's descendant should remain a descendant). It can be proven that there is a unique answer.
+
+Return the root of the trimmed binary search tree. Note that the root may change depending on the given bounds.
+
+
+Example 1:
+Input: root = [1,0,2], low = 1, high = 2
+Output: [1,null,2]
+
+Example 2:
+Input: root = [3,0,4,null,2,null,null,1], low = 1, high = 3
+Output: [3,2,null,1]
+ 
+
+Constraints:
+- The number of nodes in the tree is in the range [1, 104].
+- 0 <= Node.val <= 104
+- The value of each node in the tree is unique.
+- root is guaranteed to be a valid binary search tree.
+= 0 <= low <= high <= 104
+
+*/
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+
+/**
+ * @param {TreeNode} root
+ * @param {number} low
+ * @param {number} high
+ * @return {TreeNode}
+ */
+const trimBST = (root, low, high) => {};