20240225 Finished

src/problem/mod.rs

@@ -51,4 +51,5 @@ mod p102_binary_tree_level_order_traversal;
 mod p107_binary_tree_level_order_traversal_ii;
 mod p103_binary_tree_zigzag_level_order_traversal;
 mod p105_construct_binary_tree_from_preorder_and_inorder_traversal;
-mod p106_construct_binary_tree_from_inorder_and_postorder_traversal;
+mod p106_construct_binary_tree_from_inorder_and_postorder_traversal;
+mod p235_lowest_common_ancestor_of_a_binary_search_tree;

src/problem/p235_lowest_common_ancestor_of_a_binary_search_tree.rs

@@ -0,0 +1,58 @@
+/**
+ * [235] Lowest Common Ancestor of a Binary Search Tree
+ */
+pub struct Solution {}
+
+use crate::util::tree::{TreeNode, to_tree};
+
+// submission codes start here
+
+// Definition for a binary tree node.
+// #[derive(Debug, PartialEq, Eq)]
+// pub struct TreeNode {
+//   pub val: i32,
+//   pub left: Option<Rc<RefCell<TreeNode>>>,
+//   pub right: Option<Rc<RefCell<TreeNode>>>,
+// }
+// 
+// impl TreeNode {
+//   #[inline]
+//   pub fn new(val: i32) -> Self {
+//     TreeNode {
+//       val,
+//       left: None,
+//       right: None
+//     }
+//   }
+// }
+use std::rc::Rc;
+use std::cell::RefCell;
+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 (root, p, q) = (root?, p?, q?);
+        let mut ancestor = root;
+
+        loop {
+            ancestor =  if p.borrow().val < ancestor.borrow().val && q.borrow().val < ancestor.borrow().val {
+                Rc::clone(&ancestor.borrow().left.as_ref().unwrap())
+            } else if (p.borrow().val > ancestor.borrow().val && q.borrow().val > ancestor.borrow().val ) {
+                Rc::clone(&ancestor.borrow().right.as_ref().unwrap())
+            } else {
+                break;
+            }
+        } 
+
+        Some(ancestor)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_235() {
+    }
+}