Add solution #235

Author: JoshCrozier

0653-two-sum-iv---input-is-a-bst.js

@@ -63,6 +63,7 @@
 226|[Invert Binary Tree](./0226-invert-binary-tree.js)|Easy|
 232|[Implement Queue using Stacks](./0232-implement-queue-using-stacks.js)|Easy|
 234|[Palindrome Linked List](./0234-palindrome-linked-list.js)|Easy|
+235|[Lowest Common Ancestor of a Binary Search Tree](./0235-lowest-common-ancestor-of-a-binary-search-tree.js)|Easy|
 237|[Delete Node in a Linked List](./0237-delete-node-in-a-linked-list.js)|Easy|
 242|[Valid Anagram](./0242-valid-anagram.js)|Easy|
 263|[Ugly Number](./0263-ugly-number.js)|Easy|

README.md

@@ -0,0 +1,36 @@
+/**
+ * 235. Lowest Common Ancestor of a Binary Search Tree
+ * https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/
+ * Difficulty: Easy
+ *
+ * Given a binary search tree (BST), find the lowest common ancestor (LCA) of two
+ * given nodes in the BST.
+ *
+ * According to the definition of LCA on Wikipedia: “The lowest common ancestor is
+ * defined between two nodes p and q as the lowest node in T that has both p and q
+ * as descendants (where we allow a node to be a descendant of itself).”
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+
+/**
+ * @param {TreeNode} root
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {TreeNode}
+ */
+var lowestCommonAncestor = function(root, p, q) {
+  if (p.val > root.val && q.val > root.val) {
+    return lowestCommonAncestor(root.right, p, q);
+  }
+  if (p.val < root.val && q.val < root.val) {
+    return lowestCommonAncestor(root.left, p , q);
+  }
+  return root;
+};