#249 Lowest Common Ancestor of a Binary Search Tree

Author: forest000014

lowest-common-ancestor-of-a-binary-search-tree/forest000014.java

@@ -0,0 +1,28 @@
+/*
+# Time Complexity: O(n)
+# Space Compleixty: O(1)
+*/
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+
+class Solution {
+    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+        // null check unnecessary
+
+        if (root.val > p.val && root.val > q.val) {
+            return lowestCommonAncestor(root.left, p, q);
+        } else if (root.val < p.val && root.val < q.val) {
+            return lowestCommonAncestor(root.right, p, q);
+        } else {
+            return root;
+        }
+    }
+}