lowest-common-ancestor-of-a-binary-search-tree (#2622)

DaleSeo · web-flow · commit b56124ae2a73 · 2026-06-03T20:32:02.000-04:00
diff --git a/lowest-common-ancestor-of-a-binary-search-tree/DaleSeo.rs b/lowest-common-ancestor-of-a-binary-search-tree/DaleSeo.rs
@@ -0,0 +1,30 @@
+// TC: O(h)
+// SC: O(1)
+use std::cell::RefCell;
+use std::rc::Rc;
+
+impl Solution {
+    pub fn lowest_common_ancestor(
+        root: Option<Rc<RefCell<TreeNode>>>,
+        p: Option<Rc<RefCell<TreeNode>>>,
+        q: Option<Rc<RefCell<TreeNode>>>,
+    ) -> Option<Rc<RefCell<TreeNode>>> {
+        let p_val = p?.borrow().val;
+        let q_val = q?.borrow().val;
+        let mut current = root;
+
+        while let Some(node) = current {
+            let node_ref = node.borrow();
+            if p_val < node_ref.val && q_val < node_ref.val {
+                current = node_ref.left.clone();
+            } else if p_val > node_ref.val && q_val > node_ref.val {
+                current = node_ref.right.clone();
+            } else {
+                drop(node_ref);
+                return Some(node);
+            }
+        }
+
+        None
+    }
+}
