Add solution #669

Author: JoshCrozier

README.md

@@ -502,6 +502,7 @@
 664|[Strange Printer](./0664-strange-printer.js)|Hard|
 667|[Beautiful Arrangement II](./0667-beautiful-arrangement-ii.js)|Medium|
 668|[Kth Smallest Number in Multiplication Table](./0668-kth-smallest-number-in-multiplication-table.js)|Hard|
+669|[Trim a Binary Search Tree](./0669-trim-a-binary-search-tree.js)|Medium|
 670|[Maximum Swap](./0670-maximum-swap.js)|Medium|
 680|[Valid Palindrome II](./0680-valid-palindrome-ii.js)|Easy|
 684|[Redundant Connection](./0684-redundant-connection.js)|Medium|

solutions/0669-trim-a-binary-search-tree.js

@@ -0,0 +1,38 @@
+/**
+ * 669. Trim a Binary Search Tree
+ * https://leetcode.com/problems/trim-a-binary-search-tree/
+ * Difficulty: Medium
+ *
+ * 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.
+ */
+
+/**
+ * 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}
+ */
+var trimBST = function(root, low, high) {
+  if (!root) return null;
+
+  if (root.val < low) return trimBST(root.right, low, high);
+  if (root.val > high) return trimBST(root.left, low, high);
+  root.left = trimBST(root.left, low, high);
+  root.right = trimBST(root.right, low, high);
+
+  return root;
+};