[Jeehay28] WEEK 13

lowest-common-ancestor-of-a-binary-search-tree/Jeehay28.js

@@ -0,0 +1,67 @@
+// 🚀 Iterative approach (No recursion)
+// ✅ Time Complexity: O(h), where h is the height of the tree
+// ✅ Space Complexity: O(1) (better space efficiency)
+
+/**
+ * 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) {
+  let node = root;
+
+  while (node) {
+    if (p.val < node.val && q.val < node.val) {
+      node = node.left;
+    } else if (node.val < p.val && node.val < q.val) {
+      node = node.right;
+    } else {
+      return node;
+    }
+  }
+};
+
+
+// 🚀 Recursive approach
+// ✅ Time Complexity: O(h), where h is the height of the tree
+// ✅ Space Complexity: O(h) (due to recursion stack)
+// 🔍 The function moves down the BST recursively:
+//    - If both p and q are smaller, search the left subtree
+//    - If both p and q are larger, search the right subtree
+//    - Otherwise, root is the LCA
+
+/**
+ * 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.left, p, q);
+//   }
+
+//   if (root.val < p.val && root.val < q.val) {
+//     return lowestCommonAncestor(root.right, p, q);
+//   }
+
+//   return root;
+// };
+