solve: lowest common ancestor of a BST

Author: sounmind

lowest-common-ancestor-of-a-binary-search-tree/evan.js

@@ -0,0 +1,29 @@
+/**
+ * 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 (root.val < p.val && root.val < q.val) {
+    return lowestCommonAncestor(root.right, p, q);
+  }
+
+  if (root.val > p.val && root.val > q.val) {
+    return lowestCommonAncestor(root.left, p, q);
+  }
+
+  return root;
+};
+
+/**
+ * Time Complexity: O(h), where h is the height of the binary search tree.
+ * Space Complexity: O(h), where h is the height of the binary search tree.
+ */