Create 0101-symmetric-tree.rs

Author: raul-sauco

rust/0101-symmetric-tree.rs

@@ -0,0 +1,24 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+impl Solution {
+    // Time O(n) - Space O(h)
+    pub fn is_symmetric(root: Option<Rc<RefCell<TreeNode>>>) -> bool {
+        // An internal function that checks two nodes situated in a
+        // symmetrical position in the tree.
+        fn dfs(left: Option<Rc<RefCell<TreeNode>>>, right: Option<Rc<RefCell<TreeNode>>>) -> bool {
+            match (left, right) {
+                (None, None) => true,
+                (None, Some(_)) | (Some(_), None) => false,
+                (Some(left), Some(right)) => {
+                    left.borrow().val == right.borrow().val
+                        && dfs(left.borrow().left.clone(), right.borrow().right.clone())
+                        && dfs(left.borrow().right.clone(), right.borrow().left.clone())
+                }
+            }
+        }
+        match root {
+            Some(root) => dfs(root.borrow().left.clone(), root.borrow().right.clone()),
+            None => true,
+        }
+    }
+}