20240209 Finished

src/problem/mod.rs

@@ -41,4 +41,5 @@ mod p292_nim_game;
 mod p1696_jump_game_vi;
 mod lcp30_magic_tower;
 mod p2641_cousins_in_binary_tree_ii;
-mod p993_cousins_in_binary_tree;
+mod p993_cousins_in_binary_tree;
+mod p236_lowest_common_ancestor_of_a_binary_tree;

src/problem/p236_lowest_common_ancestor_of_a_binary_tree.rs

@@ -0,0 +1,69 @@
+/**
+ * [236] Lowest Common Ancestor of a Binary 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>>> {
+        if root.is_none() || root == p || root == q {
+            return root;
+        }
+
+        let left = Solution::lowest_common_ancestor(
+            root.as_ref().unwrap().borrow_mut().left.take(),
+            p.clone(),
+            q.clone()
+        );
+
+        let right = Solution::lowest_common_ancestor(
+            root.as_ref().unwrap().borrow_mut().right.take(),
+            p.clone(),
+            q.clone()
+        );
+
+        if left.is_some() && right.is_some() {
+            return root;
+        }
+
+        if left.is_some() {
+            left
+        } else {
+            right
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_236() {
+    }
+}